1. /_2 and /_5 are supplementary-----Given
2. /_ 3 ≅ /_2-----Vertical Angles Theorem. Vertical angles are congruent
3. /_3 and /_5 are supplementary-----Transitive Property or Same-side Interior Theorem. If /_2 and /_5 are supplementary then /_3 and /_5 are supplementary
4. l║m----- For lines cut by a traversal and same-side interior angles are supplementary the lines are parallel
