A tourist sailed against the current on a river for 6 km, and then he sailed in a lake for 15 km. In the lake he sailed for 1 hour longer than he sailed in the river. Knowing that the current of the river is 2 km/hour, find the speed of the boat while it is traveling in the lake.

Answer 1

rate of sailing in still water , assuming the lake has no current ---- x km/h
rate of sailing in river against current -- x-2 km/h

time in river = 6/(x-2)
time in lake = 15/x

the difference in those times is = 1

form the equation and solve for x
hint: I would multiply each term by x(x-2) to eliminate the fractions.

Let me know what you get.

Answer 2

2 or 5