PSAT Math Multiple-Choice Question 520: Answer and Explanation

Question: 520

What is the value of a in the equation ?

• A. 16
• B. 24
• C. 48
• D. 106

Correct Answer: C

Explanation:

C

The question asks for the value of a that satisfies an equation. There are specific values in the answers, so plug in the answers. Begin by labeling the answers as a, and start with (B), 24. Plug this value into the equation to see if it makes the equation true. The equation becomes or . This is not true, so eliminate (B). Since (B) is too small, (A) can also be eliminated. Plug (C), 48, into the equation. The equation becomes or . This is true, so stop here. Another way to approach this is by solving the equation for the value of a. To solve for a, cross-multiply to get (8) (12) = 2a or 96 = 2a. Divide both sides by 2 to get 48 = a. Either way, the correct answer is (C).