Big Ideas Math: Modeling Real Life, Grade 7
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Exercise 6 Page 173

Use the Addition Property of Equality to eliminate the subtraction.

v=- 1/24

Practice makes perfect
To solve the equation, we have to isolate v on one side. Using the Addition Property of Equality, we will add 5/6 to both sides of the equation. This will eliminate the subtraction. Let's do it!
v-5/6=- 7/8
v-5/6+5/6=- 7/8+5/6
v=- 7/8+5/6
â–Ľ
Simplify
v=- 7* 3/8* 3+5/6
v=- 21/24+5/6
v=- 21/24+5* 4/6* 4
v=- 21/24+20/24
v=- 21/24+20/24
v=- 21+20/24
v=- 1/24
v=- 1/24
To check that this solution is correct, let's substitute v=- 124 into the original equation and simplify.
v-5/6=- 7/8
- 1/24-5/6? =- 7/8
â–Ľ
Simplify
- 1/24-5* 4/6* 4? =- 7/8
- 1/24-20/24? =- 7/8
- 1/24-20/24? =- 7/8
- 1-20/24? =- 7/8
- 21/24? =- 7/8
- 7/8? =- 7/8
- 7/8=- 7/8 âś“
Since the left-hand side and right-hand side are equal, v=- 124 is the correct solution.

Extra

Properties of Equality

There are four main Properties of Equality that we use when solving linear equations.

Properties of Equality
Addition Property of Equality If a=b, then a+c=b+c.
Subtraction Property of Equality If a=b, then a-c=b-c.
Multiplication Property of Equality If a=b, then ac=bc.
Division Property of Equality If a=b and c is not 0, then a/c=b/c.

In later chapters, you will learn about some more advanced Properties of Equality. As an example, there is a property for when we need to eliminate a radical or an exponent.

Power Property of Equality

If a=b, then a^m=b^m.