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Big Ideas Math: Modeling Real Life, Grade 7

BI

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

Cumulative Practice

Finish the assignment

Exercise 14 Page 179

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

A

When adding or subtracting fractions, they should have the same denominator. In this exercise, we have two fractions with different denominators. - 4/5+(- 2/3)Since 15 is a multiple of 5 and 5, we can start by multiplying both the numerator and denominator of - 45 by 3 to create a common denominator.

- 4/5+(- 2/3)

a/b=a * 3/b * 3

- 4* 3/5* 3+(- 2/3)

Multiply

- 12/15+(- 2/3)

a/b=a * 5/b * 5

- 12/15+(- 2* 5/3* 5)

Multiply

- 12/15+(- 10/15)

Now that we have a common denominator, we can proceed to simplifying the expression.

- 12/15+(- 10/15)

a+(- b)=a-b

- 12/15-10/15

MoveNegFracToNum

Put minus sign in numerator

-12/15-10/15

Subtract fractions

-12-10/15

Subtract term

- 22/15

MoveNegNumToFrac

Put minus sign in front of fraction

- 22/15

This result corresponds to answer A.

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