We have two parallel lines crossed by a transversal.
c-
w and 25° are alternate interior angles.
Alternate interior angles are equal.
w= 25°
b.
z and 25 are supplementary angles, both add to 180°.
z + 25 =1 80
z= 180 - 25
z = 155°
a.
x and z are vertical angles. vertical angles are equal
x = z
x= 155°