Chapter 1, Equations and Inequalities - 1.2 Evaluate and Simplify Algebraic Expressions - 1.2 Exercises - Skill Practice - Page 15: 52

$$ 9 + 12 \div (3-1) =15 $$

Recall, according to PEDMAS, parenthesis are always the first order of operations. Thus, to make it a true statement, we can use parenthesis to change the order of operations. For instance, multiplication is generally done before subtraction, but if the subtraction is inside parenthesis, the subtraction is done first. Thus, we obtain: $$ 9 + 12 \div (3-1) =15 $$