PSAT Math Grid-Ins Question 109: Answer and Explanation

Question: 109

–8x + 3y = 20

–4x – 2y = 3

The ordered pair (x, y) is a solution to the system of equations above. What is the value of y?

Correct Answer: 2

Explanation:

2

The question asks for the value of a variable in a system of equations. The point of intersection will be the x and y solutions to the system, so solve the system of equations using stacking and adding. To make the x terms disappear, multiply the second equation by –2. The second equation becomes –2(–4x – 2y) = –2 (3) or 8x + 4y = –6. Now stack the equations and add them together.

Divide both sides of the resulting equation by 7 to get y = 2. The correct answer is 2.

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