You invested $11,000 in two accounts paying 8% and 9% annual interest, respectively. If the total interest earned for the year was $980, how much was invested at each rate?

X * 8/100 * 1 + 9/100 * (11,000 - x) = 980

0.08 x + 0.09 (11000 - x) = 980 Now solve for x which is the amount invested at 8%

0.08x + 990 - 0.09x = 980

- 0.01x = 980 - 990 = - 10

x = - 10 / - 0.01

x = 1000

So he invest 1000 in 8% and 10000 at 9%