Answer
$$V=18\pi$$
Work Step by Step
$V=\pi \int_0^3(4-x)^2-(4-3)^2 dx$
$V=\pi\int_0^3[(x^2-8x+16)-(1)^2] dx$
$V=\pi\int_0^3(x^2-8x+15) dx$
$V=\pi [\frac{x^3}{3}-4x^2+15x)]_0^3$
$V=\pi[(\frac{3^3}{3}-4(3)^2+15(3))-(\frac{(0)^3}{3}-4(0)+15(0))]$
$V=\pi[(9-36+45)-(0)]$
$V=18\pi$