Given: DE ∥ BC

AD = x cm

DB = (3x + 4) cm

AE = (x + 3) cm

EC = (3x + 19) cm

To find: x

∵ DE ∥ BC

∴ By Basic Proportionality theorem, we have

⇒ x (3x + 19) = (x + 3) (3x + 4)

⇒ 3x² + 19x = 3x² + 13x + 12

⇒ 19x – 13x = 3x² + 12 – 3x²

⇒ 6x = 12 or x = 2