SOLUTION: If $10,000 is invested part at 7% and part at 9%, and if the total return is $840, how much was invested at 7% ?

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Question 22219: If $10,000 is invested part at 7% and part at 9%, and if the total return is $840, how much was invested at 7% ?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Let amount invested at 7% be "x"
Then amount invested at 9% is "10000-x"
I=Pr
EQUATION:
7% interest + 90% interest = $840
0.07x + 0.09(10000-x) = 840
7x + 90000-9x = 84000
-2x = -6000
x = 3000 (amount invested at 7%)
10000-x = 7000 (amount invested at 9%)
Cheers,
Stan H.