Question

two trains moving with the speed 50 km per hour and 60 km per hour start at the same time from two station 345 km apart if both the run is opposite direction after how many hours they cross each other

Answer 1

Question is nonsensical as worded. The way the question is worded the trains either never cross paths(trains both move away from each other) , or they cross paths just the once(trains move towards each other provided each has its own track).