Answer:
Step-by-step explanation:
The amount of interest earned in one year is the product of the interest rate and the amount invested at that rate. The total interest earned is the sum of the amounts of interest earned on each investment.
Let x represent the lower interest rate. Then the higher rate is x+0.03 and the total interest earned is ...
1100x +1300(x+0.03) = 255
2400x +39 = 255 . . . simplify
2400x = 216 . . . . . . subtract 39
x = 216/2400 = 0.09 = 9% . . . . divide by the coefficient of x
Rosa invested $1100 at 9%, and $1300 at 12%.