Speed and time physics

Question

Two locomotives approach each other on parallel tracks. Each has a speed of 155 km/h with respect to the ground. If they are initially 8.5 km apart, how long will it be before they reach each other?

Answer 1

Well as they are going at the same speed in opposite directions they will meet each other when each has travelled 8.5 / 2 = 4.25 km. Time = distance / speed, so it will be 4.25 / 155 hours before they meet each other.