Rectangle Pryamid

Rectangle $ABCD$ is the base of pyramid $PABCD$. If $AB = 8$, $BC = 4$,
$\overline{PA}\perp \overline{AB}$, $\overline{PA}\perp\overline{AD}$, and PA = 6, then what is the volume of $PABCD$?

$\begin{array}{|rcll|} \hline V &=& \frac13 \cdot G \cdot h \\ &=& \frac13 \cdot (4\cdot 8) \cdot 6 \\ &=& 4\cdot 8 \cdot 2 \\ &=& 64 \\ \hline \end{array}$