(i) ∵∠x+ 125°= 180°
∠x = 180°- 125° = 55°
Two lines intersect each other
∴ ∠y = 125° (vertically opposite angles)
(ii) ∠x + 20° = 180°
[ ∠x = 180° – 20°= 160°]
(iii) Two lines intersect each other
∠x = 55° (vertically opposite angles)
∵ ∠x + ∠z = 180° (x, z is a linear pair whose sum is 180°)
55° + ∠z = 180°
⇒ ∠z = 180°- 55°= 125°
Clearly ∠y + ∠x = 90°
∠y + 55° = 90°
∠y = 90° – 55° = 35°