Two trains left at the same time towards each other from two cities, the distance between which is 600 km.

Two trains left at the same time towards each other from two cities, the distance between which is 600 km. The speed of the first train is 70 km / h, and the speed of the second train is 80 km / h. What was the distance between trains 3 hours after leaving? How long after the release did they meet?

1) Let’s find the distance at which two trains approach each other, in one hour of movement. To do this, add up their speeds:

70 + 80 = 150 (km);

2) Let’s find the distance to which two trains approached in three hours of movement:

150 * 3 = 450 (km);

3) To find what the distance was between the trains after a given time, you need to subtract from the distance between two cities the distance at which the trains approached each other in a given time.

Then:

600 – 450 = 150 (km);

4) To find how much time after the exit the trains met, you need to divide the distance between the cities by the distance by which the trains approached each other in a given time:

600: 150 = 4 (h).