You gotta remember that

means

.
So, in this case, f(x) is [4x - 3], g(x) is [x^3 + 2x].
So that : f(x)-g(x) = [4x-3] - [x^3+ 2x] = -x^3 + 4x - 2x - 3 = -x^3 + 2x - 3
After simplifying, the answer comes to x-y. I Hope this helped :).
answer this should be it 15460
First add what's in the parenthesis 1/2(3)(12)
then multiply 2 and 12 to get 1/2(36)
finally divide 36 by 2 and get 13