Question

Please help. I really don't get it

Answer 1

Answer is 4hours

Explanation

since train 1 is going 70mph away from the station and train 2 is going 80 mph in one hour the gap between them will be 150 since one train is 80miles away from the station and the other is 70miles away you add both for the distance away from each other so the growing distance each hour is 150mph and 600mph divided by 150mph is 4