Volume of the pile
$V_{pile} = 7(36)(12)$
$V_{pile} = 3024 \, \text{ ft}^3$
Volume of one brick
$V_{brick} = \dfrac{2}{12} \left( \dfrac{4}{12} \right)\left( \dfrac{9}{12} \right)$
$V_{brick} = \dfrac{1}{24} \, \text{ ft}^3$
Number of bricks in the pile
$= \dfrac{V_{pile}}{V_{brick}}$
$= \dfrac{3024}{\frac{1}{24}}$
$= 72\,576 \, \text{ bricks}$ answer