Question 7
Square $ABCD$ has side length 10 cm, and $O$ is the midpoint of $AC$. Through $B$, draw a line parallel to $AC$ and choose $K$ on it as shown. Let $M=DK\cap AC$, $N=KA\cap BC$, and $H=KO\cap MN$. Find the difference between the areas of quadrilaterals $CMHK$ and $AOHN$, in square centimetres.
