This is a right triangle so the hight if it will be 15 ft and the base will be 8ft, then we can use the formula of the areas that is:
[tex]\frac{\text{base}\cdot\text{hight}}{2}=A[/tex]so we replace the values like:
[tex]\begin{gathered} \frac{15\cdot8}{2}=A \\ 60=A \end{gathered}[/tex]So the area of the triangle is 60ft