Question 1146170
<br>
V = (1/2)bh<br>
The height is 2 feet less than the base, so<br>
base = x
height = x-2<br>
The volume is 40:
{{{(1/2)(x)(x-2) = 40}}}
{{{x(x-2) = 80}}}<br>
That's a quadratic equation; solve it by your favorite method.<br>
If an algebraic solution is not required, a very little bit of mental arithmetic should allow you to find two numbers that differ by 2 and whose product is 80.