Question

find x,y,z with reasons when AB is parallel to CD and CD is parallel to EF.

Answer 1

Here,
CD || EF and DE as transversal,

angle Y + angle DEF = 180°. (sum of consecutive interior angles)
=> y + 40 = 180
=> y = 180 - 40
=> y = 140°

Now,
AB || CD and BD as transversal,

angle x= angle y (corresponding angles)
=> x = 140°

Now,
AB is a straight line and ray BD stands on it

angle x + angle ABD = 180°. (linear pair)
=> 140 + angle ABD = 180
=> angle ABD = 180 - 140
=> angle ABD = 40°

Now, in triangle AEB,
Angle a + angle B + angle e = 180. (angle sum property of triangle)
=> 90 + 40 + z = 180
=> z = 180 - (90 + 40)
=> z = 180 - 130
=> z = 50°

That's your answer.

Hope it'll help.. :-D