Haji rows his canoe 10 mph in still water. He noticed one day that he could row 4 miles upstream in the same amount of time he could row 6 miles downstream. What was the approximate speed of the current that day?

Question

amistre64 · Answer

well, distance is equal to speed, times time.

4 = (10-c)t
6 = (10+c)t

solving for t we would have:

4/(10-c) = 6/(10+c)

solve for c

amistre64 · Answer

the current reduces your rowing speed upstream, and adds to it going down stream ... hence the 10 +- c parts