Answer:
After 2h s
Explanation:
The the whole journey is 600 km from city M to N. So the mid point would be 300 km
The bus takes 5 h to reach the mid point of the road ( 300 km ÷ 60 km/h = 5 h)
And the truck takes 6 h to reach the mid point of the road ( 300 km ÷ 50 km/h = 6 h)
So if they want to meet each other the bus should start its journey one hour after the truck.