Problem $7$: $(10$ points$)$ Setup, but DO NOT EVALUATE, an integral or sum of integrals that give the volume of the described solids.

$($a$.)$ The solid obtained by rotating the region bounded by $y=\frac{3}{2}x,y=5-x,$ and $x=0,$ about the $y-$axis.

$($b$.)$ The solid obtained by rotating the region bounded by $y=\frac{3}{2}x,y=5-x,$ and $y=0,$ about the $y-$axis.