<PRE><B>Question 177764</B>
A boat took 5 h to travel 60km up a river, against the current. The return trip
 took 3 h. Find the speed of the boat in still water and the speed of the current.
:
Let x = boat speed in still water
Let y = current speed
then
(x-y) = effective speed up-stream
and
(x+y) = effective speed down stream
:
write two distance equations:
dist = time * speed
:
5(x-y) = 60
3(x+y) = 60
simplify both equations, divide the 1st one by 5, the 2nd one by 3 and you have:
x - y = 12
x + y = 20
-------------addition eliminates y, find x:
2x = 32
x = {{{32/2}}}
x = 16 km/hr boat speed in still water
then
16 + y = 20
y = 20 - 16
y = 4 km/hr current speet
:
:
check solution by finding the dist of both
5(16-4) = 60
3(16+4) = 60
</PRE>