Question 1208172
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Trains A and B both started at the same time going in the same direction at different speeds, with B having a "head start" of 60km.<br>
Train A catches up to train B at a rate equal to the difference of their speeds -- at 30km each hour.<br>
Since train A catches up to train B at a rate of 30km each hour, and since it needs to make up a distance of 60km, the number of hours it takes train A to catch up to train B is 60/30 = 2.<br>
So when train A catches up to train B, it has traveled 2 hours at 90km/h, a distance of 180km; train B started 60km from P and traveled 2 hours at 60km/h, putting it at a distance of 60+2(60) = 180km from P.<br>
Train C started from Q and headed towards P at 120km/h. I started 1 hour later that the other two trains, so it traveled 1 hour at 120km/h, a distance of 120km.<br>
Trains A, B, and C reached the same place at the same time.  At that time, trains A and B were 180km from P and train C was 120km from Q.  So the distance from P to Q was 180+120 = 300km.<br>
ANSWER: 300km<br>