angle BCA = 180 - 100
angle BCA = 80
Isosceles triangle ABC has two congruent angles, A and B
2x + 80 = 180
2x = 100
Angles A and B = 50 or y and z = 50
I think lines AB and DE are supposed to be parallel, so angles y and x are consecutive interior angles (supplementary)
x = 180 - 50 = 130