Question 880679
A boat traveled 198 miles downstream and back.
 The trip downstream took 11 hours.
 The trip back took 33 hours.
 What is the speed of the boat in still water?
:
Let s = boat speed in still water
Let c = rate of the current
then
(s+c) = effective speed down-stream
and
(s-c) = effective speed up-stream
:
Write a distance equation for each way; dist = time * speed
11(s+c) = 198
33(s-c) = 198
We can simplify this, divide the 1st equation by 11, the 2nd equation by 33
s + c = 18
s - c = 6
-----------addition eliminates c, find s
2s = 24
s = 24/2
s = 12 mph in still water
:
:
You can confirm this, find the current then substitute in the original equations