Question 137267
 Rita paddled upstream (against the current) at an average speed of 2 mi/h relative to the riverbank. On the return trip downstream (with the current), her average speed was 3 mi/h. Find Rita's paddling speed in still water and the speed of the river's current.
:
Let s = speed in still water.
Let c = speed of the current
:
Write an equation for each trip
s - c = 2; upstream
s + c = 3; downstream
-------------adding eliminates c
2s = 5
s = {{{5/2}}}
s = 2.5 mph in still water
:
c = 3 - 2.5
c = .5 mph speed of the current
;
Check in the upstream equation : 2.5 - .5 = 2 mph