invest 12,000 in 2 funds paying 4.5% and 5% interest

Question

you plan to invest $12,000 in two funds paying 4.5% and 5% interest. at the end of the year you have $580 from your investments. how much did you invest at 4.5% and how much did you invest at 5%?

Answer 1

4.5X + 5(12K-X) = 58000

-.5X = 58-60 K

X = 2 K / .5 = 4K = $4,000

12K-4K = $8,000

4,000 at 4.5% gives 180 interest

and 8,000 at 5% gives 400 interest

180 + 400 = $580 interest