Ratio of A:B:C speeds=5:3:4

A and C meet after 1 hour, so the total distance traveled by them equals to 5x.60+ 4x.60, where x is in metres per minute.

So the time taken by A to reach out the distance= distance/speed= (5x+4x).60/ 5x= 108 minutes. Time taken by B and C are in the ratios by 5/3 and 5/4 which means 180 minutes and 135 minutes respectively.

Hope that you have got your answer.