2015 CIMC keystage3-IWYMIC team Question 8

$M$ is a point on the side $AB$ of a parallelogram $ABCD$ such that $AM:MB=4:3$. $DM$ and $CM$ are perpendicular respectively to $AC$ and $BD$. If $BC=5$ cm, find the area, in cm$^2$, of $ABCD$.