Aidan, please use more parentheses so that there's no question about what's being divided by what.
I am unsure whether the final " /a " indicates division of (b+3) by a or division of the entire expression before " /a " by a.
Here is the way I'm going to interpret your math problem:
b 2(b+3)
a+5 - ------ + ---------
b-4 a
Subbing 2 for a and 3 for b, we get
3 2(3+3)
2 + 5 - --------- + -------------
3-4 2
12
This comes out to 7 + 3 + ------ = 10+6 = 16
2
