In the given figure, AB || CD, CD || EF

and y : z = 3 : 7.

Let y = 3a and z = 7a

∠DHI = y (vertically opposite angles)

∠DHI + ∠FIH = 180°

(Interior angles on the same side of the transversal)

⇒ y + z = 180°

⇒ 3a + 7a = 180°

⇒ 10a = 180° ⇒ a = 18°

∴ y = 3 × 18° = 54° and z = 18° × 7 = 126°

Also, x + y = 180°

⇒ x + 54° = 180°

∴ x = 180° – 54° = 126°

Hence, x = 126° **Ans.**