Parallel Lines Practice NO LINKS PLEASE and please explain this for me so i can understand

Answer:
Step-by-step explanation:
The angle that is on the same side of the transversal as 102 but to the right of it, is supplementary to 102. Call this angle y
y + 102 = 180 Subtract 102 from both sides
y +102-102 = 180-102 Combine
y = 78
y and x are vertically opposite each other. They are equal
x = y
x = 78