Boat can travel 15 kph(speed) in still water, 40 km downstream in a river,same time it takes to travel 25 km upstream. Speed of the water in the river?

Question

Representations, equation, solution, and final answer 

Answer 1

d=rt

40=(15+c)t

25=(15-c)t

40/(15+c)=t

25/(15-c)t

40/(15+c)=25/(15-c)

40(15-c)=25(15+c)

600-40c=375+25c

600-375=40c+25c

225=65c

c=225/65

c=3.46 kph answer

check:

40/18.46=2.1668 hours

25/11.54=2.1663 hours