Answer:
Explanation:
The interior is a parallelogram when adjacent angles are supplementary. This requires ...
 (x -30)° + (x +50)° = 180°
 2x + 20 = 180 . . . . . . . . . . . collect terms, divide by °
 2x = 160 . . . . . . . . . . . . . . . subtract 20
 x = 80 . . . . . . . . . . . . . . . . . divide by 2
Then the angle x+50 is ...
 (x +50)° = (80 +50)° = 130°
This is also the measure of the angle marked y.
For the lines to be parallel, x = 80, y = 130°.