To build a box, you find a square piece of cardboard that measures 10 inches on each side. From each corner of the cardboard, you cut out congruent squares. Use the picture to find the area of the cardboard you will use for your box.

The correct answer is 64 square units.

The area of the complete shape would be 100 square inches.
10 x 10 = 100

However, we have to remove the 4 corners. Each of the corners is 9 square inches. 3 x 3 = 9

100 - 4(9) = 64