PSAT Math Multiple-Choice Question 244: Answer and Explanation

Question: 244

Chantal buys new furniture using store credit, which offers five-year no-interest financing. She sets up a payment plan to pay the debt off as soon as possible. The function 40 x + y = 1,400 can be used to model her payment plan where x is the number of payments Chantal has made and y is the amount of debt remaining. If a solution to the equation is (21, 560), which of the following statements is true?

• A. Chantal pays $21 per month.
• B. Chantal pays $560 per month.
• C. After 21 payments, $560 remains to be paid.
• D. After 21 payments, Chantal will have paid off $560 of the debt.

Correct Answer: C

Explanation:

C

Difficulty: Medium

Category: Heart of Algebra/Linear Equations

Getting to the Answer: Pay careful attention to what the question tells you about the variables. The x-value is the number of payments already made and the y-value is the amount of debt remaining (not how much has been paid). If a solution is (21, 560), the x-value is 21, which means Chantal has made 21 payments already. The y-value is 560, which means $560 is the amount of debt left to be paid, making (C) correct.