A train leaves station A travelling at 30mph going to Station B105 miles away 30 minutes later a Train leaves station B travelling towards station A at 60mph How far, are they from station A when they pass?
During that 30 minutes the train from A will have gone 15 miles, so it's then 90 miles between it and the train leaving B.
A does 30 miles in 1 hour. B does 60 miles in 1 hour, so they meet 1 hour after B leaves. So 60 miles from B, and 45 from A. (As stated above)