SOLUTION: George earned $12,000 last year by giving tennis lessons. He invested part at 3% simple interest and the rest at 4%. He earned a total of $440 in interest. How much did he invest a

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Question 211026: George earned $12,000 last year by giving tennis lessons. He invested part at 3% simple interest and the rest at 4%. He earned a total of $440 in interest. How much did he invest at each rate?
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
.04X+.03(12,000-X)=440
.04X+360-.03X=440
.01X=440-360
.01X=80
X=80/.01
X=8,000 AMOUNT INVESTED @ 4%.
12,000-8,000=4,000 AMOUNT INVESTED @ 3%.
PROOF:
.04*8,000+.03*4,000=440
320+120=440
440=440