Write a system of equations for the problem, and then solve the system.
-Paul invested twice as much money in an account paying 6% interest than he did in an account paying 3% interest. If the total interest paid was $ 300, how much did he invest in each?
A) $ 40 at 6%, $ 20 at 3%
B) $ 2000 at 6%, $ 4000 at 3%
C) $ 4000 at 6%, $ 2500 at 3%
D) $ 4000 at 6%, $ 2000 at 3%

Question

Quizplus · Accepted Answer

Let x be the amount invested at 3% and 2x be the amount invested at 6%. The total interest from both investments is $300. The equation for the interest from the 3% investment is 0.03x, and for the 6% investment, it's 0.06(2x) = 0.12x. Adding these gives the total interest: 0.03x + 0.12x = 0.15x. Setting this equal to $300 gives 0.15x = 300, solving for x gives x = $2000 at 3% and 2x = $4000 at 6%.

Write a System of Equations for the Problem, and Then