volume of the trapezoidal prism is
[tex]V=A_b\times h[/tex]then, area of the trapezoidal base
[tex]\begin{gathered} A_b=\frac{1}{2}(b1+b2)h \\ A_b=\frac{1}{2}(10+20)\times12 \\ A_b=\frac{1}{2}(30)\times12 \\ A_b=\frac{360}{2}=180 \end{gathered}[/tex]area of the trapezoidal base = 180 ft^2
height = 2ft
so, the volume is:
[tex]\begin{gathered} V=180\times2 \\ V=360 \end{gathered}[/tex]volume = 360 ft^3