John builds a box. The box is 26 inches by 26 inches by 14 inches. The walls are 1 inch thick on each side. How much is the internal volume in cubic feet? Think carefully first, then make a decision:
The walls take away 2 * 1 = 2 inches from each dimension. So the longer sides are 26 - 2 = 24 inches. That is 24 / 12 = 2 feet. The smaller dimension is 14 - 2 = 12 inches. That is 12 / 12 = 1 foot. So the internal volume is 2 * 2 * 1 = 4 cubic feet. So, the answer is 4.