Answer:
780 km
Step-by-step explanation:
Let the distance from Picture Rock to Rockville is d km.
Now, the time taken by the passenger train with speed 78 km/hr to cover this distance will be [tex]\frac{d}{78}[/tex] hours.
Again the time taken by the freight train with speed 52 km/hr to cover the distance will be [tex]\frac{d}{52}[/tex] hours.
Now, by the condition given we can write [tex]\frac{d}{52} - \frac{d}{78} = 5[/tex]
⇒ [tex]d(\frac{78-52}{78 \times 52} )=5[/tex]
⇒ d = 780 km. (Answer)
