Question 790926
let s = speed in still water
let c = speed of the current
then
(s+c) = effective speed downstream
and
(s-c) - effective speed upstream
:
Write a distance equation of each way; dist = time * speed
:
"paddle their canoe 26 miles downstream in 2 hours."
2(s+c) = 26
:
"they paddle upstream. after 3 hours they have traveled only 9 miles back."
3(s-c) = 9
:
Simplify both equations, divide the first by 2, the 2nd by 3 and you have:
s + c = 13
s - c = 3
-----------Addition eliminates c, find s
2s = 16
s = 8 mph in still water