The difference between the area of the big and small squares is 40 square meters, and the sum of the side lengths is 20 meters

The difference between the area of the big and small squares is 40 square meters, and the sum of the side lengths is 20 meters

Side length difference: 40 △ 20 = 2 (CM)
Side length: (20 + 2) △ 2 = 11 (CM)
(20-2) △ 2 = 9 (CM)
Area: 11 × 11 = 121 (square centimeter)
9 × 9 = 81 (square centimeter)