9. (10 points) In the figure, $ABCD$ is a parallelogram, $E$ is the midpoint of $CD$, the intersection of $AE$ and $BD$ is $F$, the intersection of $AC$ and $BE$ is $H$, the intersection of $AC$ and $BD$ is $G$, the area of quadrilateral $EHGF$ is 15 square centimeters, then the area of $ABCD$ is $\qquad$ square centimeters.