A person rows a boat at 18 km/h downstream and 10 km/h upstream. What are the speeds of the person in still water and the current, respectively?

Explanation

Let the speed of the person in still water be x km/h and the speed of the stream be y km/h. According to the problem, x + y = 18 (downstream speed) and x - y = 10 (upstream speed). Adding these two equations gives 2x = 28, so x = 14 km/h. Substituting back, y = 4 km/h. Therefore, the speed in still water is 14 km/h and the speed of the stream is 4 km/h.