To find the volume of a rectangular prism, you would use the formula V = l*w*h, where l is the length, w is the width, and h is the height.
Plugging in the values:
V = (2 1/4 ft) * (1 1/2 ft) * (3/4 ft)
V = (9/4 ft) * (3/2 ft) * (3/4 ft)
V = (27/8 ft^3)
V = 3 3/8 ft^3
Therefore, the volume of the moving box is 3 3/8 cubic feet.