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

Exercise #1

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 #2

(+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 #3

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 #4

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 #5

(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 #6

(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 #7

(+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 #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

(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 #10

(0.85)+(+2.25)= (-0.85)+(+2.25)= ?

Video Solution

Step-by-Step Solution

First, locate -0.85 on the number line and note that we are moving 2.25 steps to the right:

-0.85-0.85-0.85000+2.25

Then use the commutative property:

2.250.85= 2.25-0.85=

Finally, solve vertically:

2.250.85=1.40 2.25\\-0.85\\=1.40

Answer

1.4 1.4

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

(+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 #13

Solve the following expression:

(+0.68)+(+12.03)= ? (+0.68)+(+12.03)=\text{ ?}

Video Solution

Step-by-Step Solution

Given that we are adding two positive numbers together, the result will be positive.

Looking at the numbers, we know that the result must be greater than 12.

Then we can proceed to use simple addition to solve as follows:

0.68+12.0312.71 0.68\\+12.03\\12.71

Answer

12.71 12.71

Exercise #14

(0.43)(0.87)= (-0.43)-(-0.87)=

Video Solution

Step-by-Step Solution

Let's first consider the rule:

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

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

0.43+0.87= -0.43+0.87=

We'll use the distributive property and solve the exercise step by step:

0.870.430.44 0.87\\-0.43\\0.44

Answer

0.44 0.44

Exercise #15

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 #16

(+19)+(+23)= ? (+\frac{1}{9})+(+\frac{2}{3})=\text{ ?}

Video Solution

Step-by-Step Solution

Let's multiply the numerator and denominator of the fraction 23 \frac{2}{3} by 3 and the numerator and denominator of the fraction 19 \frac{1}{9} by 1 in order to find a common denominator:

2×33×3=69 \frac{2\times3}{3\times3}=\frac{6}{9}

1×19×1=19 \frac{1\times1}{9\times1}=\frac{1}{9}

Finally let's perform the addition operation to find our answer:

19+69=79 \frac{1}{9}+\frac{6}{9}=\frac{7}{9}

Answer

79 \frac{7}{9}

Exercise #17

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 #18

(+7)(6.7)= (+7)-(-6.7)=

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 and solve it:

7+6.7=13.7 7+6.7=13.7

Answer

13.7 13.7

Exercise #19

(+0.27)(+1.12)= (+0.27)-(+1.12)=

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:

0.271.12= 0.27-1.12=

Since we are subtracting a smaller number from a larger number, the result will be negative.

We'll use vertical subtraction and remember that the result is negative:

1.120.270.85 1.12\\-0.27\\0.85

The final result is:

0.85 -0.85

Answer

0.85 -0.85

Exercise #20

(0.73)+(13.07)= (-0.73)+(-13.07)=

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:

0.7313.07= -0.73-13.07=

Since we are subtracting a larger number from a smaller number, the result will be negative.

We'll combine the two numbers together vertically, but remember that the result will be negative:

0.73+13.0713.80 0.73\\+13.07\\13.80

Therefore, the answer is:

0.7313.07=13.8 -0.73-13.07=-13.8

Answer

13.8 -13.8