Need with this angle don't know what to do with the x

Hello!

Due to the definition of the Alternate Interior Angles Theorem, (x+23)+(x+54)=180 degrees:

x + 23 + x + 54 = 180
2x + 77 = 180
2x = 103
x = approximately 52 degrees  or exactly 51.5 degrees

I hope this helps :))

The answer is 10 bud