geometry help me please

Given: LINE AB is parallel to LINE CD and ANGLE EIJ congruent to ANGLE GJ

Prove: angle JIK congruent to angle  IJL

What is the reason for the last step in the given proof?

1.angle EIJ  congruent to angle  GJI  ——————–>given

2. m angle EIJ = m angle GJI ——————>definition of congruent angles

3. angle EIJ and angle JIK are supplementary.——————->Linear Pair Theorem

4. m angle EIJ + m angle JIK = 180° ————–>definition of supplementary angles

5. m angle GJI + m angle JIK = 180° —————>Substitution Property of Equality

6. angle GJI and angle JIK are supplementary. ———————–>definition of supplementary angles

7. angle GJI and angle IJL are supplementary.  ————–>Linear Pair Theorem 

8. angle JIK congruent to angle IJL  —————————> MISSING PROOF?