In the following figure, if AC ∥ QR, then y = ?

Concept -

(1) The corresponding angles on the same side are equal. 

(2) ∠ABP + ∠PBC = 180∘ 

Explanation -

Let the ∠ABP = x and we have AC ∥ QR,

Now we know that -

∠ABP + ∠PBC = 180^∘ 

⇒ x + 120^∘ =180∘ ⇒ x  = 180∘ - 120∘ ⇒ x  = 60∘ 

Now we know that ∠ABP and ∠PRQ are corresponding angles.

So ∠ABP = x = y = 60∘ 

Hence the correct answer is  y = 60∘