Examples with solutions for Addition and Subtraction of Directed Numbers: Solving the problem

Exercise #1

Solve the following expression:

(+8)+(+12)= ? (+8)+(+12)=\text{ ?}

Video Solution

Step-by-Step Solution

Let's add 8 to the number line and move 12 steps to the right.

Note that our result is a positive number:

Now solve the following exercise:

8+12=20 8+12=20

Answer

20 20

Exercise #2

(8)+(12)= (-8)+(-12)=

Video Solution

Step-by-Step Solution

Let's locate -8 on the number line and move 12 steps to the left.

Let's note that our result is a negative number:

000-8-8-8-12

Let's remember the rule:

Now let's write the exercise in the appropriate form and solve it:

812=20 -8-12=-20

Answer

20 -20

Exercise #3

(10)(+13)= (-10)-(+13)=

Video Solution

Step-by-Step Solution

Let's locate -10 on the number line and move 13 steps to the left.

Let's note that our result is a negative number:

000-10-10-10-13

Let's remember the rule:

(+x)=x -(+x)=-x

Now let's write the exercise in the appropriate form and solve it:

1013=23 -10-13=-23

Answer

23 -23

Exercise #4

(8)(13)= (-8)-(-13)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the appropriate form:

8+13= -8+13=

We'll use the substitution law and solve:

138=5 13-8=5

Answer

5 5

Exercise #5

Solve the following expression:

(+8)+(4.5)= ? (+8)+(-4.5)=\text{ ?}

Video Solution

Step-by-Step Solution

First we need to locate the number 8 on the number line and move 4.5 steps to the left from it:

000888

Remember the rule:

+(x)=x +(-x)=-x

Now let's rewrite the problem in the appropriate form and solve:

84.5=3.5 8-4.5=3.5

Answer

3.5 3.5

Exercise #6

(+567)(69)= (+567)-(-69)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the appropriate form:

567+69= 567+69=

Let's solve the exercise vertically:

567+69636 567\\+69\\636

Answer

636 636

Exercise #7

(+301)+(51)= ? (+301)+(-51)=\text{ ?}

Video Solution

Step-by-Step Solution

First, remember the rule:

+(x)=x +(-x)=-x

Place 301 on the number line and move 51 steps to the left:

000301301301-51

Rewrite the exercise in the appropriate form and solve it:

30151=250 301-51=250

Answer

250 250

Exercise #8

Solve the following problem

(+6)(+11)= (+6)-(+11)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(+x)=x -(+x)=-x

Now let's write the exercise in the appropriate form:

611= 6-11=

We'll locate the number 6 on the number line and from there we'll move 11 steps to the left:

111-2-2-2-1-1-1000-3-3-3-4-4-4666222333444555-5-5-5

The answer is minus 5.

Answer

5 -5

Exercise #9

Solve the following equation:

(8)+(+12)= ? (-8)+(+12)=\text{ ?}

Video Solution

Step-by-Step Solution

First, let's remember the rule:

+(+x)=+x +(+x)=+x

Now let's write the exercise in the following way:

8+12= -8+12=

We'll draw a number line and place minus 8 on it, then move 12 steps to the right:

-1-1-1-4-4-4-3-3-3-2-2-2-5-5-5-6-6-6-8-8-8-7-7-7444000111222333

Therefore:

8+12=4 -8+12=4

Answer

4 4

Exercise #10

Solve the following exercise:

(17)(77)= (-\frac{1}{7})-(-\frac{7}{7})=

Step-by-Step Solution

Let's position minus 17 \frac{1}{7} on the number line and move one step to the right, since 77=11=1 \frac{7}{7}=\frac{1}{1}=1

We should note that our result is a positive number:

000+1

Let's remember the rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the appropriate form and solve it:

17+1=67 -\frac{1}{7}+1=\frac{6}{7}

Answer

67 \frac{6}{7}

Exercise #11

(+14)+(234)= ? (+\frac{1}{4})+(2\frac{3}{4})=\text{ ?}

Video Solution

Step-by-Step Solution

First, locate the number 14 \frac{1}{4} on the number line and move 234 2\frac{3}{4} steps to the right from it.

This means the resulting number will be positive:

Finally, solve the exercise:

14+234=3 \frac{1}{4}+2\frac{3}{4}=3

Answer

3

Exercise #12

(15)+(+313)= (-\frac{1}{5})+(+3\frac{1}{3})=

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Convert 313 3\frac{1}{3} to an improper fraction.
  • Step 2: Find a common denominator for 15 -\frac{1}{5} and the improper fraction.
  • Step 3: Add the fractions.
  • Step 4: Simplify the result, converting it back to a mixed number if necessary.

Now, let's work through each step:

Step 1: Convert 313 3\frac{1}{3} to an improper fraction.
313=3×3+13=103 3\frac{1}{3} = \frac{3 \times 3 + 1}{3} = \frac{10}{3}

Step 2: Find a common denominator for 15 -\frac{1}{5} and 103 \frac{10}{3} .
The least common denominator of 5 and 3 is 15.

Step 3: Express each fraction with the common denominator:
15=315 -\frac{1}{5} = -\frac{3}{15} (multiply the numerator and denominator by 3)
103=5015 \frac{10}{3} = \frac{50}{15} (multiply the numerator and denominator by 5)

Step 4: Add the fractions:
315+5015=3+5015=4715 -\frac{3}{15} + \frac{50}{15} = \frac{-3 + 50}{15} = \frac{47}{15}

Step 5: Simplify 4715 \frac{47}{15} back to a mixed number if needed:
Performing the division, 47 divided by 15 is 3 with a remainder of 2.
Therefore, 4715=3215 \frac{47}{15} = 3\frac{2}{15} .

Therefore, the solution to the problem is 3215 3\frac{2}{15} .

Answer

3215 3\frac{2}{15}

Exercise #13

(+1313)(+714)= (+13\frac{1}{3})-(+7\frac{1}{4})=

Video Solution

Step-by-Step Solution

To solve the problem of subtracting +714 +7\frac{1}{4} from +1313 +13\frac{1}{3} , we follow these steps:

  • Convert 1313 13\frac{1}{3} to an improper fraction:

1313=393+13=39+13=403 13\frac{1}{3} = \frac{39}{3} + \frac{1}{3} = \frac{39 + 1}{3} = \frac{40}{3}

  • Convert 714 7\frac{1}{4} to an improper fraction:

714=284+14=28+14=294 7\frac{1}{4} = \frac{28}{4} + \frac{1}{4} = \frac{28 + 1}{4} = \frac{29}{4}

  • Find a common denominator for 403\frac{40}{3} and 294\frac{29}{4}. The least common multiple of 3 and 4 is 12.
  • Convert 403\frac{40}{3} to a fraction with a denominator of 12:

403×44=16012\frac{40}{3} \times \frac{4}{4} = \frac{160}{12}

  • Convert 294\frac{29}{4} to a fraction with a denominator of 12:

294×33=8712\frac{29}{4} \times \frac{3}{3} = \frac{87}{12}

  • Subtract the fractions:

160128712=1608712=7312\frac{160}{12} - \frac{87}{12} = \frac{160 - 87}{12} = \frac{73}{12}

  • Convert 7312\frac{73}{12} back to a mixed fraction:

73÷12=673 \div 12 = 6 remainder 11, so it equals 6112 6\frac{1}{12} .

Therefore, the solution to the problem is 6112 6\frac{1}{12} .

Answer

6112 6\frac{1}{12}

Exercise #14

Solve the following problem:

(15)+(345)= (-\frac{1}{5})+(-3\frac{4}{5})=

Video Solution

Step-by-Step Solution

Let's mark minus 15 \frac{1}{5} on the number line and move 345 3\frac{4}{5} steps to the left, meaning our result will be a negative number:

000

Let's remember the rule:

+(x)=x +(-x)=-x

Now let's write the exercise in the appropriate form and solve it:

15345=4 -\frac{1}{5}-3\frac{4}{5}=-4

Answer

4 -4

Exercise #15

(+15)(+334)= (+\frac{1}{5})-(+3\frac{3}{4})=

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Convert the mixed number to an improper fraction.

  • Find a common denominator for the fractions.

  • Perform the subtraction.

Now, let's work through each step:

Step 1: Convert the Mixed Number
Convert 334 3\frac{3}{4} to an improper fraction:

334=3×4+34=12+34=154 3\frac{3}{4} = \frac{3 \times 4 + 3}{4} = \frac{12 + 3}{4} = \frac{15}{4} .

Step 2: Find a Common Denominator
Identify a common denominator for 15 \frac{1}{5} and 154 \frac{15}{4} . The least common denominator (LCD) of 5 and 4 is 20.

Convert 15 \frac{1}{5} and 154 \frac{15}{4} to have denominator 20:

15=1×45×4=420 \frac{1}{5} = \frac{1 \times 4}{5 \times 4} = \frac{4}{20} and 154=15×54×5=7520 \frac{15}{4} = \frac{15 \times 5}{4 \times 5} = \frac{75}{20} .

Step 3: Subtract the Fractions
Subtract the fractions:

4207520=47520=7120 \frac{4}{20} - \frac{75}{20} = \frac{4 - 75}{20} = \frac{-71}{20} .

The resulting fraction can be converted back to a mixed number:

7120=31120 \frac{-71}{20} = -3\frac{11}{20} .

Therefore, the solution to the problem is 31120 -3\frac{11}{20} .

Answer

31120 -3\frac{11}{20}

Exercise #16

Solve the following expression:

(302)(7.6)= (-302)-(-7.6)=

Video Solution

Step-by-Step Solution

Note the following rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the appropriate form:

302+7.6= -302+7.6=

We'll locate -302 on the number line and go right 7.6 steps:

-302-302-302+7.6

Note that our result will be negative.

Let's solve the exercise carefully by adding a decimal point to the number 302 to avoid confusion during the solution:

302.07.6294.4 302.0\\-7.6\\294.4

Note that the final answer is negative, meaning:

294.4 -294.4

Answer

294.4 -294.4

Exercise #17

(1314)+(927)= (-13\frac{1}{4})+(-9\frac{2}{7})=

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Convert mixed numbers to improper fractions.
  • Step 2: Find the least common denominator.
  • Step 3: Perform the addition and convert back to a mixed number.

Let's work through each step:

Step 1: Convert mixed numbers to improper fractions.

1314 -13\frac{1}{4} = (13+14)=(524+14)=534 -\left( 13 + \frac{1}{4} \right) = -\left( \frac{52}{4} + \frac{1}{4} \right) = -\frac{53}{4}

927 -9\frac{2}{7} = (9+27)=(637+27)=657 -\left( 9 + \frac{2}{7} \right) = -\left( \frac{63}{7} + \frac{2}{7} \right) = -\frac{65}{7}

Step 2: Determine a common denominator. The least common multiple of 4 and 7 is 28.

Convert the fractions:

534=53×74×7=37128 -\frac{53}{4} = -\frac{53 \times 7}{4 \times 7} = -\frac{371}{28}

657=65×47×4=26028 -\frac{65}{7} = -\frac{65 \times 4}{7 \times 4} = -\frac{260}{28}

Step 3: Add the fractions:

37128+(26028)=371+26028=63128 -\frac{371}{28} + \left(-\frac{260}{28}\right) = -\frac{371 + 260}{28} = -\frac{631}{28}

Converting 63128 -\frac{631}{28} back to a mixed number:

Perform the division: 631÷2822 631 \div 28 \approx 22 remainder 15.

This gives us a mixed number: 221528 -22\frac{15}{28}

Therefore, the solution to the problem is 221528 -22\frac{15}{28} .

Answer

221528 -22\frac{15}{28}

Exercise #18

(+0.76)(+13.04)= ? (+0.76)-(+13.04)=\text{ ?}

Video Solution

Step-by-Step Solution

First we need to remember the rule:

(+x)=x -(+x)=-x

Now let's rewrite the exercise in the appropriate form:

0.7613.04= 0.76-13.04=

Next we will solve the exercise vertically, keeping in mind that the final result will be negative since we are subtracting a smaller number from a larger number:

13.040.7612.28 13.04\\-0.76\\12.28

Remember that the answer must be a negative number, so we will add a minus sign to get:

12.28 -\text{12}.28

Answer

12.28 -12.28

Exercise #19

(1714)(+1118)= (-17\frac{1}{4})-(+11\frac{1}{8})=

Video Solution

Step-by-Step Solution

To solve the problem (1714)(+1118)(-17\frac{1}{4}) - (+11\frac{1}{8}), we need to perform the following steps:

  • Step 1: Convert each mixed number to an improper fraction.
    1714-17\frac{1}{4} converts to an improper fraction as follows:
    1714=(17×4+14)=(68+14)=(694).-17\frac{1}{4} = -\left(\frac{17 \times 4 + 1}{4}\right) = -\left(\frac{68 + 1}{4}\right) = -\left(\frac{69}{4}\right).
    +1118+11\frac{1}{8} converts to an improper fraction as follows:
    +1118=(11×8+18)=(88+18)=(898).+11\frac{1}{8} = \left(\frac{11 \times 8 + 1}{8}\right) = \left(\frac{88 + 1}{8}\right) = \left(\frac{89}{8}\right).
  • Step 2: Ensure both fractions have a common denominator. Here, the least common denominator (LCD) between 4 and 8 is 8.
    (694)-\left(\frac{69}{4}\right) must be converted to have a denominator of 8:
    (69×24×2)=(1388).-\left(\frac{69 \times 2}{4 \times 2}\right) = -\left(\frac{138}{8}\right).
  • Step 3: Perform the subtraction:
    Subtraction: (1388)(898)=(138+898)=(2278).-\left(\frac{138}{8}\right) - \left(\frac{89}{8}\right) = -\left(\frac{138 + 89}{8}\right) = -\left(\frac{227}{8}\right).
  • Step 4: Convert the result back to a mixed number, if necessary.
    Divide 227 by 8: 227÷8=28227 \div 8 = 28 with a remainder of 3. Hence, the result is:
    (28+38)=2838.-\left(28 + \frac{3}{8}\right) = -28\frac{3}{8}.

Therefore, the solution to the problem is 2838-28\frac{3}{8}.

Answer

2838 -28\frac{3}{8}

Exercise #20

(1214)(827)= (-12\frac{1}{4})-(-8\frac{2}{7})=

Video Solution

Step-by-Step Solution

Let's solve the problem step-by-step:

  • Step 1: Convert mixed numbers to improper fractions.

For 1214-12\frac{1}{4}, convert to an improper fraction:

1214=(12+14)=(484+14)=494-12\frac{1}{4} = -\left(12 + \frac{1}{4}\right) = -\left(\frac{48}{4} + \frac{1}{4}\right) = -\frac{49}{4}

For 827-8\frac{2}{7}, convert to an improper fraction:

827=(8+27)=(567+27)=587-8\frac{2}{7} = -\left(8 + \frac{2}{7}\right) = -\left(\frac{56}{7} + \frac{2}{7}\right) = -\frac{58}{7}

  • Step 2: Subtract the second improper fraction from the first.

The operation becomes 494(587)-\frac{49}{4} - (-\frac{58}{7}), which simplifies to 494+587-\frac{49}{4} + \frac{58}{7}.

Find a common denominator for 494\frac{49}{4} and 587\frac{58}{7}. The least common denominator is 28.

Convert 494-\frac{49}{4} and 587\frac{58}{7} to equivalents with a denominator of 28:

494=49×74×7=34328-\frac{49}{4} = -\frac{49 \times 7}{4 \times 7} = -\frac{343}{28}

587=58×47×4=23228\frac{58}{7} = \frac{58 \times 4}{7 \times 4} = \frac{232}{28}

So, 494+587-\frac{49}{4} + \frac{58}{7} becomes:

34328+23228=343+23228=11128-\frac{343}{28} + \frac{232}{28} = \frac{-343 + 232}{28} = \frac{-111}{28}

  • Step 3: Simplify the improper fraction 11128\frac{-111}{28} to a mixed number form.

Divide 111-111 by 28, which gives 3-3 and a remainder of 27. Thus:

32728-3\frac{27}{28}

Therefore, the solution to the problem is 32728-3\frac{27}{28}.

Answer

32728 -3\frac{27}{28}