Question : A boat covers a distance of 72 km downstream in 6 hours, while it takes 12 hours to cover the same distance upstream. What is the speed of the boat in still water?

Question : A man covers a certain distance by bike. If he covers 25% of the distance at the speed of 25 km/hr, 50% of the distance at the speed of 50 km/hr and the remaining distance at the speed of 12.5 km/hr, find his average speed over the whole journey.

Question : The speed of a boat in still water is 20 km/hr, while the river is flowing at a speed of 8 km/hr and the time taken to cover a certain distance upstream is 6 hr more than the time taken to cover the same distance downstream. Find the distance.

Question : A man has to be at a certain place at a certain time. He finds that he shall be 20 minutes late if he walks at 3 km/hr speed and 10 minutes earlier if he walks at a speed of 4 km/hr. The distance he has to walk is:

Question : A person takes 40 minutes more than his usual time when he covers a distance of 20 km at 5 km/hr. If he covers the same distance at 8 km/hr, he takes $x$ minutes less than the usual time. What is the value of $x$?