2010 xIMC keystage2-EMIC individual Question 10

Rectangle $ABCD$ has $AB=4$, $BC=6$ cm. Points $E,F,G,H$ lie on $AB,BC,CD,DA$, with $AE=CG=3$, $BF=DH=4$ cm. Interior point $P$ satisfies $[AEPH]=5$ cm$^2$. Find $[PFCG]$.