In the figure above, $\overline{AF},\overline{BE},$ and $\overline{CD}$ are parallel. Points $B$ and $E$ lie on $\overline{AC}$ and $\overline{FD}$, respectively. If $AB=7.5,BC=12.5,$ and $FE=6,$ what is the length of $\overline{FD}$?