Explanation:
- JK = LM
 - L is midpoint of JN ⇒ JL = LN = 1/2JN
 - JK║LM and JN is a transversal ⇒ 
 
 ∠KJL and ∠MLN are corresponding angles ⇒ 
 ∠KJL ≅ ∠MLN
We have two sides and the included angle of ΔJLK congruent to two sides and the included angle of ΔLNM
Therefore ΔJLK ≅ ΔLNM by SAS rule