Answer:
4 miles
Explanation:
Let the distance between the police station and the fire station be x
Now we are given that the distance between the library and the police station is 3 miles less than twice the distance between the police station and the fire station.
So, distance between the library and the police station =

Now we are given that The distance between the library and the police station is 5 miles
So,




Hence the police station and the fire station are 4 miles apart.