Question 1024237
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A Canoe traveled Downstream with the current and went a distance of 15 miles in three hours. 
On the return trip, the canoe traveled Upstream against the current. It took 5 hours to make the return trip. Find the rate of the current.
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Let u = the canoe speed in still water (the speed relative to water), in mph.
    v = the speed of the current.

When canoe travels downstream, its speed relative to the bank of the river is the sum u + v, and it is equal to

u + v = {{{15/3}}}     (speed = {{{distance/time)}}}).

When canoe travels upstream, its speed relative to the bank of the river is the difference u - v, and it is equal to

u - v = {{{15/5}}}     (again, speed = {{{distance/time)}}}).

Rewrite these equations with calculated right sides:

u + v = 5,      (1)
u - v = 3.      (2)

Now add equations (1) and (2) (both sides). You will get

2u = 5 + 3 = 8.

Hence, u = {{{8/2}}} = 4 mph. It is the canoe speed in still water.

Next,  from (1)  v = 5 - u = 5 - 4 = 1 mph. It is the current speed.
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