algebra investments
posted by Anonymous .
Peter invested some money at 6% annual interest and martha invested some at 12%. If their investments is $6000 and their combined interest was $540. How much money did martha invest?

Let Peter's investment be x
then Martha's investment is 6000x
solve:
.06x + .12(6000x) = 540
6x + 12x(6000x) = 54000
I am sure you can finish it.