Question 21
Let $ABCDEF$ be a convex hexagon such that $AB \parallel DE$, $BC \parallel EF$ and $CD \parallel FA$. Let $H$, $I$, $J$, $K$, $L$ and $M$ be the midpoints of sides $AB$, $BC$, $CD$, $DE$, $EF$ and $FA$, respectively. Prove that lines $HK$, $IL$ and $JM$ are concurrent.