What is the missing statement for the last step of Mandy's proof?

Definition of perpendicular lines

If 2 angles are congruent to equal angles, then the 2 angles are congruent.

The transitive property of equality

If 2 angles are complementary to congruent angles, then the 2 angles are congruent.

What is the missing statement for the last step of Mandys proof Definition of perpendicular lines If 2 angles are congruent to equal angles then the 2 angles ar class=