Let L = length W = L - 5 ←5 feet less than (reverse order - ) the length (L) D = L + 5 These 3 lengths form a right triangle with D being the hypotenuse, c. Using the Pythagorean Theorem, a² + b² = c² L² + (L - 5)² = (L + 5)² L² + L² - 10L + 25 = L² + 10L + 25 L² - 20L = 0 L = 0 (can't use this answer) or L = 20 (this is a usable answer) Dimensions of the sandbox 20 ft by 15 ft Length = 20 ft Width = 15 ft Diagonal = 25 ft