Question

Sally invested a total of $4500, some at 9% per year and the rest at 6% per year. The return from the 9% investment exceeds that from the 6% investment by $180. How much did she invest at each rate?

Answer 1

I can't tell you how to set it up but I can tell you that she invested $3000 at 9% and $1500 at 6%.

3000 x .09 = 270
1500 x .06 = 90
270 - 90 = 180

Answer 2

let the amount invested at 9% be x
then the amount invested at 6% is 4500-x

.09x + .06(4500-x) = 180

solve for x