Step-by-step explanation:
∠2 = 77°
∠2 = ∠4 ( being vertically opposite angle )
∠4 = 77°
Now...
∠1 + ∠2 = 180° ( supplementary angle )
∠1 = 180° - 77°
∠1 = 103°
here....
∠1 = ∠3 ( vertically opposite angle )
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