[The ratio of the areas of triangles with a common base or common height $]$ Complex Trapezoids (other)

The area of trapezoid $A B C D$ with bases $A D$ and $B C (A D > B C)$ is 48, and the area of triangle $A O B$, where $O-$ is the point of intersection of the diagonals of the trapezoid, is 9. Find the ratio of the bases of the trapezoid $A D: B C$.