ANSWER
[tex]81ft^2[/tex]
EXPLANATION
The area of a trapezoid is generally given as:
[tex]A=\frac{1}{2}(a+b)h[/tex]
where a = length of short base
b = length of long base
h = height
Therefore, we have that the area of the trapezoid is:
[tex]\begin{gathered} A=\frac{1}{2}(3+15)\cdot9=\frac{1}{2}\cdot18\cdot9 \\ A=81ft^2 \end{gathered}[/tex]
