Answer:
At the nearest mile, stations B and C are 75 miles apart.
Explanation:
In the attached image we can see all the three stations. The closest distance between stations B and C would be a straight line that can be calculate using the Cosine Rule:
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Where:
AB is the distance between stations A and B
AC is the distance between stations A and C
α is the angle formed between the AC and AB railway lines


So, at the nearest mile, stations B and C are 75 miles apart.