Question 158595
Your calculations are correct.

The amount invested at 7% is $9000
The amount invested at 5% is $4500.

This statement is wrong : .05(13,500 - 9000)=4500
It should be 0.05*(13500-9000) = 225

If that is the reason your instructor is rejecting your answer, I feel for you. It will be a really long year in a classroom with a nit picker like that :(