Big Ideas Math: Modeling Real Life, Grade 7
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Big Ideas Math: Modeling Real Life, Grade 7 View details
3. Solving Two-Step Equations
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Exercise 29 Page 143

Start by subtracting 2 from both sides.

b = 13 12

Practice makes perfect
To solve an equation, we should first gather all of the variable terms on one side and all of the constant terms on the other side using the Properties of Equality. In this case, the only variable term is already on the left-hand side of the equation, so we will start by subtracting 2 from both sides.
2-b/3=- 5/2
- b/3+2=- 5/2
- b/3+2-2=- 5/2-2
- b/3=- 5/2-2
â–Ľ
Simplify right-hand side
- b/3=- 5/2-4/2
- b/3=- 5/2-4/2
- b/3=- 5 -4/2
- b/3=- 9/2
Now, we are going to multiply the equation by - 3 using the Multiplication Property of Equality to eliminate the fraction. Let's go!
- b/3=- 9/2
b/- 3=- 9/2
b/- 3 * (- 3) =- 9/2 * (- 3)
b =- 9/2 * (- 3)
b =- 9(- 3)/2
â–Ľ
Multiply
b =9 * 3/2
b =27/2
b = 13 12
The solution to the equation is b = 13 12. We can check our solution by substituting it into the original equation.
2-b/3=- 5/2
2-13 12/3 ? = - 5/2
â–Ľ
Simplify
2-13 * 2 + 12/3 ? = - 5/2
2-26 + 12/3 ? = - 5/2
2-272/3 ? = - 5/2
2-27/3 * 2 ? = - 5/2
2-27/6 ? = - 5/2
12/6-27/6 ? = - 5/2
12-27/6 ? = - 5/2
- 15/6 ? = - 5/2
- 15/3/6/3 ? = - 5/2
- 5/2 ? = - 5/2
- 5/2=- 5/2
Since the left-hand side is equal to the right-hand side, our solution is correct.