(It should be 5 kilometers from the midpoint. )
When they met, there were more buses than trucks: 5× 2 = 10 (km).
The ratio of this 10km to the whole journey is 8/(7+8)-7/(7+8) =115.
From the local to the whole, we can know that the distance of the whole is10 ÷115 =150 (km).
When the total freight car distance is 150km, the passenger car distance is150× 7 ÷ 8 =131.25 (km).
Therefore, the distance to the terminal station B is150-131.25 =18.75 (km).