<PRE><B>Question 404102</B>
Going down the river a boat went 11 mph.
 Going up the river it only went 3 mph. What is the speed of the current? How fast would the boat go if there were no current?
:
Let s = speed in still water
Let c = speed of the current
:
Two equations, use elimination here
s + c = 11
s - c =  3
---------------Addition eliminates c find s
2s = 14
s = 7 mph in still water
</PRE>