In the given figure, line AB and CD intersect at O. If ∠COB=x∘, ∠BOD=4x∘ and ∠AOD=y∘, then y= ______ .
(i) ∠COB+∠BOD=180∘ ...(linear pair) x∘+4x∘=180∘ 5x∘=180∘ x=36∘ (ii) ∠AOD=∠COB ...(vertically opposite angles) ∴y=x=36∘