TeX source:

\begin{align*} \text{Volume of Prism (Cube)}&=A_{\text{base}} \cdot h \\ &=(12 \cdot 12) (12) \\ &=1728 \ {\text{ft}}^3 \\ \text{Volume of Pyramid} &=\frac{A_{\text{base}} \cdot h}{3}\\ & =\frac{(12 \cdot 12) (10)}{3}\\ & =480 \ \text{ft}^3 \\ \text{Total Volume} & = \text{Volume of Prism (Cube)}+ \text{Volume of Pyramid} \\ &=1728+480 \\ & =2208 \ \text{ft}^3\end{align*}