h = 12 feet
a = 10 feet
b = 15 feet
[tex]\begin{gathered} \text{area of a trapezoid}=\frac{1}{2}(a+b)h \\ \end{gathered}[/tex][tex]\begin{gathered} area=\frac{1}{2}(10+15)12 \\ \text{area}=\frac{1}{2}(25)12 \\ \text{area}=\frac{300}{2} \\ \text{area}=150ft^2 \end{gathered}[/tex]