SOLUTION: A certain sum of money is invested at 10%. Twice that amount is invested at 8%. The total amount of interest from both investments is $91. How much is invested at 8%?

Question 204322: A certain sum of money is invested at 10%. Twice that amount is invested at 8%. The total amount of interest from both investments is $91. How much is invested at 8%?
Answer by Earlsdon(6294) (Show Source): You can put this solution on YOUR website!
Let x = the amount invested at 10%, then 2x is the amount invested at 8%.
The interest earned on these two amounts can be expressed as:
Simplify the left side.

Divide both sides by 0.26
and...

$700 is invested at 8%
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