∵ Ray AE stands on line GH ∴AEG + ∠AEH = 180°
| Linear Pair Axiom
⇒ 50° + x = 180°
⇒ x = 180° - 50° = 130° ...(1)
y = 130° ...(2)
| Vertically Opposite Angles
From (1) and (2), we conclude that
x = y
But these are alternate interior angles and they are equal.
So, we can say that AB || CD.