SOLUTION: Bob invested $22,000, part at 18% and part at 14%. If the total interest at the end of the year is $3,360, how much did he invest at 18%?

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Question 117490: Bob invested $22,000, part at 18% and part at 14%. If the total interest at the end of the year is $3,360, how much did he invest at 18%?
Answer by ankor@dixie-net.com(12704) About Me  (Show Source):
You can put this solution on YOUR website!
Bob invested $22,000, part at 18% and part at 14%. If the total interest at the end of the year is $3,360, how much did he invest at 18%?
:
Let x = amt invested at 18%
Then
(22000-x) = amt invested at 14%
:
A simple interest equation:
.18x + .14(22000-x) = 3360
:
.18x + 3080 - .14x = 3360
:
.18x - .14x = 3360 - 3080
:
.04x = 280
:
x = 280/.04
:
x = $7,000 invested at 18%
:
:
Check our solution:
22000 - 7000 = 15000 amt invested at 14%
:
.18(7000) + .14(15000) =
1260 + 2100 = 3360