Assuming both vertical lines are parallel and assuming I'm supposed to find all the unmarked angles...
Angle C:
Supplementary Angles.
x+36=180
180-36=x
x=144
Angle B:
Corresponding Angles.
Angle B ≅ Angle C
144
Angle A:
360 degrees in a quadrilateral
36+144+81+x=360
261+x=360
x = 99
Hope it helps <3
