Answer
a) 4000 $ft^3$
b) 30,000 gallons
Work Step by Step
a) The volume is:
$$ V =(160)(300)(\frac{1}{12})\\ V = 4000 ft^3 $$
b) Converting from cubic feet to gallons:
$$ =4000ft^3 \times \frac{7.5\ gallons}{ft^3} \\ \approx 30,000 \ gallons$$