Finding the angle, given that the two lines are parallel

[Mathisconfusing101]

In the figure provided, lines m and n are parallel. Find the measure of angle x.

The way the textbook page goes through this problem is confusing.. can someone explain how to solve this?

 

[Mathisconfusing101]

ok wait a sec... i just realized .. would you add the two together..

therefore it would be 55?

 

[jonboy]

Yes correct. If you add the third parallel you will see why.