От Тайынши до Кызылжара поезд шел 14 часов. Обратный путь этот
поезд прошел со скоростью на 40 км в час большей и поэтому прошел
весь путь на 4 часа быстрее. Найдите расстояние от Тайынши до
Кызылжара.

Translated to English the question is that a train went in 14 hours from Tayinshi to Kyzylzhar. On the way back, the train passed at a speed of 40 km per hour more and therefore passed 4 hours faster all the way. Find the distance from Taiynshi to Kyzylzhar.

Solution

The equation for the distance d covered at constant speed v, in time t, is:

d = v × t

For the time of 14 hours, you can write:

d = 14v

For the way back, the time is 4 hours less, 10 hours, and the speed 40km/h more, v + 40km/h, then the equation becomes:

d = 10 (v + 40)

Equal the two equations:

14v = 10(v + 40)

Solve:

14v = 10v + 400

4v = 400

v = 100 km/h

Replace v = 100km/h in the first equation:

d = 14h × 100 km/h = 1,400 km