Set up an equation that can be used to solve the problem. Solve the equation and answer the question asked.
-A college student earned $7200 during summer vacation working as a waiter in a popular restaurant. The student invested part of the money at 9% and the rest at 8%. If the student received a total of $613 in interest at
The end of the year, how much was invested at 9%?
A) $3500
B) $900
C) $3700
D) $3600

Question

Quizplus · Accepted Answer

Let the amount invested at 9% be x dollars. Therefore, the amount invested at 8% would be $7200 - x. The total interest from both investments is $613. The interest from the investment at 9% is 0.09x, and the interest from the investment at 8% is 0.08(7200 - x). The equation to represent the total interest is 0.09x + 0.08(7200 - x) = 613. Solving this equation for x gives x = $3700, which means $3700 was invested at 9%.

Set Up an Equation That Can Be Used to Solve