Math
posted by Bob .
You invested $14,000 in two accounts paying 5% and 9% annual interest, respectively. If the total interest earned for the year was $820, how much was invested at each rate?

If you have x at 5%, then you have (14000x) at 9%. Now just calculate the interest on each and add it up:
.05x + .09(14000x) = 820
x = 11000
so, you have $11,000 at 5% and $3000 at 9%.