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Big Ideas Math: Modeling Real Life, Grade 7
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Big Ideas Math: Modeling Real Life, Grade 7 View details
1. Solving Equations Using Addition or Subtraction
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Exercise 21 Page 131

Use the Addition Property of Equality to eliminate the subtraction.

p=2/3

Practice makes perfect

To solve the equation, we have to isolate p on one side. Using the Addition Property of Equality, we will add 3 16 to both sides of the equation. This will eliminate the subtraction and isolate p.

p - 3 16 = - 2 12
AddEqn

LHS+3 16=RHS+3 16

p - 3 16 + 3 16 = - 2 12 + 3 16
AddTerms

Add terms

p = - 2 12 + 3 16
â–¼
Simplify right-hand side
WriteSum

Write as a sum

p = - (2 + 1/2) + 3 + 1/6
Distr

Distribute - 1

p = - 2 - 1/2 + 3 + 1/6
CommutativePropAdd

Commutative Property of Addition

p = - 2 + 3 - 1/2 + 1/6
ExpandFrac

a/b=a * 3/b * 3

p = - 2 + 3 - 36 + 16
AddTerms

Add terms

p = 1 - 2/6
ReduceFrac

a/b=.a /2./.b /2.

p = 1 - 1/3
SubTerm

Subtract term

p = 2/3

To check that this solution is correct, let's substitute p = 23 into the original equation and simplify.

p - 3 16 = - 2 12
Substitute

p= 2/3

2/3 - 3 16 ? =- 2 12
ExpandFrac

a/b=a * 2/b * 2

4/6 - 3 16 ? =- 2 12
WriteDiff

Write as a difference

46 - 3 - 16 ? =- 2 12
SubTerm

Subtract term

3/6 - 3 ? =- 2 12
ReduceFrac

a/b=.a /3./.b /3.

1/2 - 3 ? =- 2 12
SubTerm

Subtract term

- 2 12 = - 2 12 ✓

Since the left-hand side and right-hand side are equal, p = 23 is the correct solution.

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arrow_right Try It p.128-129
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Try It 2 (Page 128)
Try It 3 (Page 128)
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arrow_right Self-Assessment for Concept & Skills p.129
Self-Assessment for Concept & Skills 5 (Page 129)
Self-Assessment for Concept & Skills 6 (Page 129)
Self-Assessment for Concept & Skills 7 (Page 129)
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arrow_right Self-Assessment for Problem Solving p.130
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arrow_right Review & Refresh p.131
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