SOLUTION: a total of $8000 is invested. part at 7% and the remainder at 15%. how much is invested at each rate if theannual intrest is 680$?

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Question 345340: a total of $8000 is invested. part at 7% and the remainder at 15%. how much is invested at each rate if theannual intrest is 680$?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Let A be the amount invested at 7%, B the amount at 15%.
1.A%2BB=8000
2.7A%2B15B=68000
Multiply eq. 1 by (-7) and add to eq. 2,
-7A-7B%2B7A%2B15B=-56000%2B68000
8B=12000
highlight%28B=1500%29
Then from eq. 1,
A%2B1500=8000
highlight%28A=6500%29