math
posted by helpme .
Mrs. Brighton invested $30,000 and received a total of $2,300 in interest. If she invested part of the money at 10% and the remainder at 5%, then how much did she invest at each rate?

.10 x + .05 (30,000x) = 2,300
10 x + 5 (30,000x)= 230,000
2 x + (30,000  x ) = 46,000
x + 30,000 = 46,000
you take it from there 
Assume that the money was left on deposit for one year. They should have told you that.
If x was invested at 10%, 30,000 x was invested at 5%
x * 0.10 + (30,000 x) * 0.05 = 2300
0.1 x + 1500  .05x = 2300
0.05 x = 800
x = 16,000 (invested at 10%)
(30,000  x) = 14,000 invested at 5%