69th Belarusian Mathematical Olympiad

The line $l$ passes through the vertex $D$ of the rectangle $ABCD$ and doesn't have any other common points with this rectangle. The point $M$ lies on $l$, and area of the triangle $MBD$ is twice the area of the triangle $MAD$. Find all possible values of the ratio of the areas of the triangles $MCD$ and $MAD$.