Exercise 8 Page 19

We want to find the sum. Let's look at the given expression! - 7/10+ 1/5 When adding or subtracting fractions they should have the same denominator. In this case, we have two fractions with different denominators. Since 10 is a multiple of 5, we can start by multiplying both the numerator and denominator of 15 by 2 to create a common denominator.

-7/10+1/5

ExpandFrac

a/b=a * 2/b * 2

-7/10+1* 2/5* 2

IdPropMult

Identity Property of Multiplication

-7/10+2/5* 2

Multiply

Multiply

-7/10+2/10

Now, we can find the sum of two numbers with different signs. Recall that to do so, we will subtract the lesser absolute value from the greater absolute value. Then, we will use the sign of the number with the greater absolute value. First, we will calculate the absolute value of the numbers. | -7/10|=7/10and| 2/10|=2/10 Notice that | - 710| is greater than | 210|. This means that we should subtract | 210| from | - 710|. Let's do it!

|- 7/10|-|2/10|

AbsNeg

|-7/10|=7/10

7/10-|2/10|

AbsPos

|2/10|=2/10

7/10-2/10

SubFrac

Subtract fractions

7-2/10

SubTerm

Subtract term

5/10

ReduceFrac

a/b=.a /5./.b /5.

1/2

WriteDec

Write as a decimal

0.5

Recall that the number with the greater absolute value is negative. This means that the sum is also a negative number, - 0.5.