Answer:
-12
Explanation:
I am assuming that you want (f*g)(4), which is the product of f and g at x = 4.
If this is actually the case, then one way to evaluate (f*g)(4) is to find f(4) and g(4) separately and then multiply the results together. This gives us
f(4)*g(4) = (8 + 4)*(-4 + 3) = -12