<PRE><B>Question 95407</B>
Rita rows 12 km upstream and 12 km downstream in 3 hours. The speed of her boat in still water is 9 km/hr. Find the speed of the stream. 
:
Let x = speed of the stream
then
(9 - x) = Boat speed up-stream
and
(9 + x) = Boat speed down-stream
:
Write a time equation: Time = dist/speed
:
Time upstream + Time downstream = 3 hrs
{{{12/((9-x))}}} +  {{{12/((9+x))}}} = 3</PRE>