Consider the figure:
If ∠B = 50∘, ∠ACD = 120∘, and x = 2y, then find the value of ∠A (in degrees).
Given, ∠ACD = 120∘
Hence, ∠ACB = 60∘ (linear pair)
Using angle sum property of triangle, in ΔABC, we have
∠A+∠B+∠C=180∘
Substiuting the given values, we have,
∠A = 70∘