Answer:
1) Vertical angles
2) Corresponding angles
3) Alternate interior angles
4) Alternate exterior angles
Explanation:
1) y x because of vertical angles
It is given that vertical angles are congruent.
2) y x because of corresponding angles
These angles are at corresponding positions of the parallel lines, so they're congruent.
3) y x because of alternate interior angles
These angles are on the inside of the parallel lines and opposite sides of the transversal, so they are congruent.
4) y x because of alternate exterior angles
These angles are on the outside of the parallel lines and opposite sides of the transversal, so they are congruent.