Question 15
$E$ and $N$ are points on the sides $DC$ and $DA$ of the square $ABCD$ such that $AN:ND:DE=2:3:4$. The line through $N$ perpendicular to $BE$ cuts $BE$ at $P$ and $BC$ at $M$. $AC$ cuts $MN$ at $O$ and $BE$ at point $S$. What fraction of the area of $ABCD$ is the area of triangle $OPS$?
