SOLUTION: Jonathon invested $8,400, part at 12 percent annual interest and the remainder at 8 percent annual interest. In one year, he earned three times as much interest from the 12 percent

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Question 1116274: Jonathon invested $8,400, part at 12 percent annual interest and the remainder at 8 percent annual interest. In one year, he earned three times as much interest from the 12 percent investment as he did from the 8 percent investment. How much interest did Jonathon earn at 8 percent interest?
The answer should be $224. How did I achieve that answer What formula should be used and where should the percentages go into the formula?
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


(1) Divide the $8400 that was invested into two parts, one to be invested at 12% and the other at 8%.

let x = amount invested at 8%
then (8400-x) = amount invested at 12%

(2) Write and solve the equation that says the interest on the amount invested at 12% was 3 times the interest on the amount invested at 8%.

interest at 12%: 0.12 times (8400-x)
interest at 8%: 0.08 times x
0.12%288400-x%29+=+3%2A0.08%28x%29

I'll let you finish from there.