52. As shown in the figure, in rectangle $A B C D$, $E, F$ are on $C D$ and $B C$ respectively, and satisfy $D E: E C=2: 3$. Connecting $A F, B E$ intersect at point $O$. If $A O: O F=5: 2$, then $B F: F C=$ $\qquad$
Answer: $2: 1$