The trunk of the car is shaped like a rectangular prism whose volume is length * width * height.
The volume of the trunk is LWH = 3 ft * 4 ft * 2 ft = 24 ft^3
The volume of a cube is the cube of the side (edge)
.
Each cubic box has volume V = s^3 = (1 ft)^3 = 1 ft^3
Now we divide the volume of the trunk by the volume of each cube box.

Answer: She can fit 24 boxes in her trunk.