Can someone me with this problem?

give the missing reasons in this proof of the alternate interior angles theorem.

given: l is parallel to n.
prove: angle 4 ≅ angle 6

1. l is parallel to n 1. given
2. angle 2 ≅ angle 6 a.
3. angle 4 ≅ angle 2 b.
4. angle 6 ≅ angle 4 c.

1. L is parallel to n 1. Given
2. angle 2 ≅ angle 6 a. corresponding angles 
3. angle 4 ≅ angle 2 b. vertical angles
4. angle 6 ≅ angle 4 c. alternate interior angles

corresponding angles are angles found in matching corners.
vertical angles are angles that share the same vertex
alternate interior angles are angles found on the opposite sides of the transversal but inside the two parallel lines

He secknd step was the answer to them