<PRE><B>Question 939811</B>
A speed boat took 3 hours to travel the distance of 60 km Up a River against the current. 
Return trip took two hours. 
Find the average speed of the boat in Still water and the speed of the current.
:
let s = boat speed in still water
let c = speed of the current
then
(s-c) = effective speed up the river
and
(s+c) = effective speed down river
:
Write a distance equation for each way; dist = time * speed
3(s-c) = 60
2(s+c) = 60
Simplify both equations, divide the 1st by 3, divide the 2nd by 2 and you have
s - c = 20
s + c = 30
------------adding eliminates c, find s
2s = 50
s = 50/s
s = 25 mph is the boat speed in still water
Find c, use the equation s + c = 30, replace s with 25
25 + c = 30
c = 30 - 25
c = 5 mph is the speed of the current
:
:
Check these solutions in the 1st original equation
3(25 - 5) = 60
3(20) = 60
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