Answer
240 $m^{2}$
Work Step by Step
The area of a trapezoid whose bases have lengths b1 and b2 and altitude has length of h is given by
A = $\frac{1}{2}$*h(b1+b2)
Lets take b1 = BC = 20m
b2 =AD = 12m
h = 15 m
Therefore A = $\frac{1}{2}$*15* (12+20)
= 15*(16) = 240 $m^{2}$
