Area of a square = side × side

Given, squares have sides x cm and (x + 4) cm. The sum of their areas is 656 cm².

⇒ x² + (x + 4)² = 656

⇒ x² + x² + 8x + 16 = 656

⇒ x² + 4x – 320 = 0

⇒ x² + 20x – 16x – 320 = 0

⇒ x(x + 20) – 16(x + 20) = 0

⇒ (x – 16)(x + 20) = 0

⇒ x = 16 cm

The other side = 16 + 4 = 20 cm