From point A to point B a train left and was on the way for 4 hours 50 minutes. How long did he spend on the way back?

The formula for solving similar problems: S = tu (The path is equal to the speed times the time). We only have time. Neither the path nor the speed is known. Let the train travel at the same speed, then it will spend the same amount of time on the way back, that is, 4 hours and 50 minutes, given that the train was traveling without stops and did not change the route.