Question 548125: John has $20,000 to invest. He invests part of his money at an annual interest rate of 6%, the rest at 9% annual rate. The return on these two investments over one year is $1,440. How much does he invest at each rate?
Answer by mananth(16946)   (Show Source):
You can put this solution on YOUR website! Fund A 6.00% per annum ---x
Fund B 9.00% per annum ---y
x + y= 20000 ------------------------1
6.00% x + 9.00% y= = $1,440.00
Multiply by 100
6 x + 9 y= = $144,000.00 --------2
Multiply (1) by -6
we get
-6 x -6 y= = -120000.00
Add this to (2)
0 x 3 y= = $24,000.00
divide by 3
y =$8,000.00 investment at 9.00%
Balance $12,000.00 investment at 6.00%
CHECK
$12,000.00 --------- 6.00% ------- $720.00
$8,000.00 ------- 9.00% ------- $720.00
Total -------------- $1,440.00
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