Question 2
Consider the nonconvex quadrilateral $ABCD$ with $\angle C>180^\circ$. Let the side $CD$ extended meet $AB$ at $F$ and the side $BC$ extended meet $AD$ at $E$. A line intersects the interiors of the sides $AB,AD,BC,CD$ at points $K,L,J,I$, respectively. Prove that if $DI=CF$ and $BJ=CE$, then $KJ=IL$.