There are two squares of different sizes. The difference in circumference is 20cm and the difference in area is 75cm. What is the area of the big square?
20 △ 4 = 5cm, side length difference 5cm
75-5 × 5 = 50 square centimeter
Side length of small square: 50 △ 2 △ 5 = 5cm
Side length of large square: 5 + 5 = 10 cm
Then the area of the large square is: 10 × 10 = 100 square centimeters