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 31 Page 131

The word is divides the sentence into what should be on the left-hand side and what should be on the right-hand side of the equation.

Equation: y + (- 3) = - 8
Solution: y = - 5

Practice makes perfect

We have been given a sentence and we need to translate it into an equation.

The sum of a number y and - 3 is - 8.

Every equation has an equals sign and values or expressions on either side of it. Key phrases, such as is, is equal to, and equals tell us about the placement of the equals sign. The sum of a numberyand- 3 is - 8. ⇕ The sum of a numberyand- 3 = - 8. On the left-hand side we have one key word: sum. This word tell us the operation that will be used in our equation. Sum indicates addition. Sum of a numberyand - 3 y + ( - 3) Putting the sides together, we have a complete equation. y + ( - 3) = - 8 Finally, we can solve the equation using the Addition Property of Equality.
y + (- 3) = - 8
y - 3 = - 8
y - 3 + 3 = - 8 + 3
y = - 5