Question

In Fig. 95, if AB, CD and EF are straight lines, then x =
(a) 5
(b) 10
(c) 20
(d) 30

Answer 1

Let all the lines intersect at O.


∠COF = ∠DOE = 4x^∘ [Vertically opposite angles]
∠AOC + ∠COF + ∠BOF = 180^∘ [AOB is a straight line]
⇒ 2x^∘ + 4x^∘ + 3x^∘ = 180^∘
⇒ 9x^∘ = 180^∘
⇒ 9x = 180
⇒ x = 20
Hence, the correct answer is option (c).