SOLUTION: Janet invested $27,000, part at 15% and part at 9%. If the total interest at the end of the year is $3,390, how much did she invest at 15%?

Question 258029: Janet invested $27,000, part at 15% and part at 9%. If the total interest at the end of the year is $3,390, how much did she invest at 15%?
Answer by drk(1908) (Show Source): You can put this solution on YOUR website!
This question is modeled after the I = prt question. IN this case however, we have two investments. So we can write
I = prt + prt
based on the given information, we get
(i)
simplifying (i) , we get
(ii)
and then
(iii)
subtracting, we get
(iv)
and dividing, we get
x = $11,777.78 @ 15%
and
27000 - x = $15,222.22 @ 9%.

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