math
posted by ximena .
things do not go quite as planned. you invested $8000, part of it in stock that paid 12% annual interest. however, the rest of the money suffered a 55 loss. if the total annual income from both investments was $620, how much was invested at each rate?

Since the total profit was 620 which included the loss of 55, there must have been a profit of 675 from the first investment.
Assuming we are looking only at the one year, the question now becomes a simple interest problem where
P ?
I = 675
R = .12
T = 1
P = I/(RT)
= 675/.12 = 5625
so he invested $5625 at 12% ( the winner) and
$2375 in the losing investment. 
what is 9000at 3%simple interest for 2and 1/2