Answer
a)
$A$ = $\frac{4}{25}(20-y)^{2}$
b)
$V$ = $\frac{1280}{3}$
Work Step by Step
a)
s = side length
y = height
$\frac{8}{20}$ =$\frac{s}{20-y}$
$s$ = $\frac{2}{5}(20-y)$
$A$ = $(s^{2}$
$A$ = $\frac{4}{25}(20-y)^{2}$
b)
$V$ = $\int_0^{20}\frac{4}{25}(20-y)^{2}dy$
$V$ = $-\frac{4}{75}(20-y)^{3}|_0^{20}$
$V$ = $\frac{1280}{3}$