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

Exercise #1

(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 #2

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 #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

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 #5

(+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 #6

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 #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 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 #9

(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 #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

Solve the following expression:

(+100)(+1.01)= ? (+100)-(+1.01)=\text{ ?}

Video Solution

Step-by-Step Solution

Note the following rule:

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

Now let's rewrite the exercise as follows:

1001.01= 100-1.01=

We should note that we are subtracting between two positive numbers, meaning we will obtain a positive result.

Therefore:

1001.0198.99 100\\-1.01\\98.99

Answer

98.99 98.99

Exercise #12

(+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 #13

(16)(426)= (-\frac{1}{6})-(-4\frac{2}{6})=

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:

16+426= -\frac{1}{6}+4\frac{2}{6}=

We'll use the substitution law and solve:

42616=416 4\frac{2}{6}-\frac{1}{6}=4\frac{1}{6}

Answer

416 4\frac{1}{6}

Exercise #14

(0.97)(+3.34)= (-0.97)-(+3.34)=

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:

0.973.34= -0.97-3.34=

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

We'll connect the two numbers but won't forget that the final result is with a minus sign:

0.97+3.344.31 0.97\\+3.34\\4.31

In other words:

0.973.34=4.31 -0.97-3.34=-4.31

Answer

4.31 -4.31

Exercise #15

(+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 #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

(+215)(3050)= (+2\frac{1}{5})-(-\frac{30}{50})=

Video Solution

Step-by-Step Solution

Let's remember the rule:

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

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

215+3050= 2\frac{1}{5}+\frac{30}{50}=

We'll reduce the fraction 3050 \frac{30}{50} by 10

215+35=245 2\frac{1}{5}+\frac{3}{5}=2\frac{4}{5}

Answer

245 2\frac{4}{5}

Exercise #18

(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 #19

(0.83)(14.68)= (-0.83)-(-14.68)=

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:

0.83+14.68= -0.83+14.68=

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

14.680.8313.85 14.68\\-0.83\\13.85

Answer

13.85 13.85

Exercise #20

(+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