42. In figure, AB || CD and CD || EF. Also EA ⊥ AB. If ∠BEF = 40°, then find x, y, z.

∵ CD || EF and a transversal DE intersects them
∴ y + 40° = 180°
| Sum of consecutive interior on the same side of a transversal is 180°
⇒ y = 180° - 40° = 140°
∵ AB || CD and a transversal BD intersects them
x = y    | Corresponding angles
⇒ x = 140°
∵ EA ⊥ AB and AB || EF
∵ EA ⊥ EF
| If a line is perpendicular to a line, then it is perpendicular to the parallel line also
⇒ ∠AEF = 90°
⇒ z + 40° = 90°
⇒    z = 50°