The Alternate Exterior Angles Theorem states that, when two parallel lines are cut by a transversal , the resulting alternate exterior angles are congruent.
Given that:
[tex]\begin{gathered} m\angle\text{LRB}=86\degree,\text{ its alternate exterior angle is }m\angle\text{CSK} \\ \\ \text{Therefore,} \\ m\angle\text{CSK}=m\angle\text{LRB} \\ m\angle\text{CSK}=86\degree\text{ (final answer)} \end{gathered}[/tex]