19. As shown in the figure, points $E$, $F$, $G$, and $H$ are the midpoints of the sides of rectangle $ABCD$, and point $O$ is any point inside the rectangle. It is known that the area of quadrilateral $EBOF$ is 30, the area of quadrilateral $OFCG$ is 40, and the area of quadrilateral $HOGD$ is 35. Then the area of quadrilateral $AEOH$ is $\qquad$.
$25$