The distance between cities A and B is 800 km. At the same time, two trains left these cities to meet each other.

The distance between cities A and B is 800 km. At the same time, two trains left these cities to meet each other. After 4 hours, there were 40 km between the trains, and they had not met yet. With what speeds did the trains move if the speed of one is 10 km / h more than the speed of the other?

Let x be the speed of the former.
Let x + 10 be the speed of the second.

Let’s make an equation.

4x + 4 * (x + 10) = 800 – 40;
4x + 4x + 40 = 760;
8x = 760 – 40;
8x = 720;
x = 720: 8;
x = 90 (km / h) – the speed of the first train.

Now let’s find the speed of the second train.

90 + 10 = 100 (km / h) – the speed of the second train.

Answer: the speed of the first train is 90 km / h, and the speed of the second train is 100 km / h.