In the fig. below, if AB || CD, ∠APQ = 50∘ and ∠PRD = 127∘, find x and y.
Since AB || CD
∠APQ = ∠PQR (Alternate interior angles of transversal PQ)
⇒ x = 50∘
∠APR = ∠PRD (Alternate interior angles of transversal PR)
⇒ y + 50∘ = 127∘
⇒ y = 127∘ - 50∘
⇒ y = 77∘.