(f*g)(x) basically just means to multiply the two functions. So does (g*f)(x). (unless it is supposed to be a composite)
Since multiplication is commutative then both a and b will have the same answer. They are binomials so you need to FOIL.
(4x-5)(3x^2-1) = 12x^3 - 15x^2 - 4x + 5
then for part c, evaluate when x=2
12(2)^3 - 15(2)^2 -4(2) + 5 = 96 - 60 - 8 +5 = 33