So everything in this problem is in terms of height (h). We'll abbreviate width to w and length to l and volume to v
l=h+7
w=h-9
a.
volume is height x width x length
v=h(h+7)(h-9)
now we have to multiply these values
h(h+7)=h^2+7h
(h^2+7h)(h-9)=h^3-9h^2+7h^2-63h=h^3-2h^2-63h
b.
now we plug in h=17
v=17^3 -2(17)^2 -63(17) = which comes out to 2686
note: **i suggest going through these steps on your own mostly because it's late and i'm tired and that seems like an awfully large number so you may want to check it
