The theorem we want to prove says that:
Two lines that are parallel to a third line are parallel.
Statement 1:
n || m and p || m
Reason 1:
Given
Statement 2:

Reason 2:
The pairs are corresponding angles
Statement 3:

Reason 3:
Transitive property of congruency, that is:

Statement 4:

Reason 4:
If the angles formed between a line and two other lines are equal, they are corresponding angles.
Statement 5:
n || p
Reason 5:
If two angles are corresponding angles, the lines that form them are parallel (this is the backwards of the reason 2).