$1500 was invested at 11%
$2500 was invested at 8%
Assuming simple interest for each investment, we have the following expressions
0.11x = interest on 11% investment. (x = amount invested at 11%)
0.08(4000-x) = interest on 8% investment
Adding the 2 expressions together and setting the sum to 365 gives
0.11x + 0.08(4000-x) = 365
Now solve for x by first distributing the 0.08
0.11x + 320 - 0.08x = 365
Subtract 320 from both sides and combine x's
0.03x = 45
Divide both sides by 0.03
x = 1500
So $1500 was invested at 11% and (4000-1500) = 2500 was invested at 8%
