Solve the problem.
-Walt made an extra $5000 last year from a part-time job. He invested part of the money at 6% and the rest at 9%. He made a total of $420 in interest. How much was invested at 9%?
A)$4000
B)$2500
C)$3000
D)$1000

Question

Quizplus · Accepted Answer

Let x be the amount invested at 9%. Then, the amount invested at 6% is $5000 - x. The interest earned from the 6% investment is 0.06(5000 - x) = 300 - 0.06x. The interest earned from the 9% investment is 0.09x. The total interest earned is 300 - 0.06x + 0.09x = 420. Solving for x, we get x = $4000.

Solve the Problem. -Walt Made an Extra $5000 Last Year from a Part-Time