Big Ideas Math: Modeling Real Life, Grade 7
BI
Big Ideas Math: Modeling Real Life, Grade 7 View details
Cumulative Practice

Exercise 8 Page 122

To add or subtract fractions, they need to have the same denominator.

H

We want to find a number equivalent to the given expression. - 2 14-(- 8 38) Before we can evaluate our expression involving mixed numbers, the mixed numbers must first be rewritten as fractions.

a bc a* c+b/c Simplify
- 2 14 - (2* 4+1/4) - 9/4
- 8 38 -(8* 8+3/8) -67/8
When adding or subtracting fractions, they should have the same denominator. In this exercise, we have two fractions with different denominators. - 2 14-(- 8 38) ⇔ - 9/4-(- 67/8) Since 8 is a multiple of 4, we can multiply both the numerator and denominator of - 94 by 2 to create a common denominator.
- 9/4-(- 67/8)
- 9* 2/4* 2-(- 67/8)
- 18/8-(- 67/8)
Now that we have a common denominator, we can proceed to simplifying the expression.
- 18/8-(- 67/8)
- 18/8+67/8
-18/8+67/8
- 18+67/8
49/8
6 18
This result corresponds to answer H.