Find the volume of solid of revolution generated by rotating the lamina contained between $\displaystyle y=4-x^2$ and $\displaystyle y=0$, around the axis $\displaystyle x=3$.

I understand the premise of this task but can't quite arrive at the correct expression for integration, which should lead me eventually to the answer of $\displaystyle 64\pi$ (if I should believe the textbook). Any ideas?

EDIT: Sorry, corrected the typo.