Answer:
68 ft³
Explanation:
Take the above figure to be 2 rectangular prism. A smaller prism on top, and a bigger one under.
Volume of the smaller rectangular prism on top:

Where,
w = 2 ft
h = 4 ft
l = 4 ft

Volume of bigger Rectangle prism under:
w = 2 ft
h = 3 ft
l = 6 ft

Volume of composite figure = 32 + 36 = 68 ft³