In the given figure, lines AB and CD intersect at O. Find the value of x+y.
72∘
85∘
95∘
88∘
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Solution
The correct option is A 72 Consider the straight line COD. Since the angles on a straight line equals 180∘, we have ∠COB+∠BOD=180∘ ⇒x∘+4x∘=180∘ ⇒5x∘=180∘ ⇒x=36∘ Now, note that ∠AOD=∠COB [vertically opposite angles] ∵y=x=36∘ ∴y+x=36∘+36∘=72∘