SOLUTION: james invested money at 9% interest. james also invested $80 more than 3 times that amount at 7%. how much is invested at each rate if james recieves $542.30 in interest after one

Question 1031590: james invested money at 9% interest. james also invested $80 more than 3 times that amount at 7%. how much is invested at each rate if james recieves $542.30 in interest after one year?
Answer by fractalier(6550) (Show Source): You can put this solution on YOUR website!
Call what he invests at 9%, x.
Then he invests (80+3x) at 7%.
The set up looks like this:
.09x + .07(80+3x) = 542.30
Multiply by 100 and get
9x + 7(80+3x) = 54230
Now solve for x...
9x + 560 + 21x = 54230
30x + 560 = 54230
30x = 53670
x = $1789 at 9%
so that
3x + 80 = 3(1789) + 80 = $5447 at 7%
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