<PRE><B>Question 1090419</B>
speed of hiking on flat ground is x
(x+1)* time=(x+1)*3=3(x+1)=3x+3 mi distance to lake
return (x-1)*6=6x-6 mi
but these distances are equal
6x-6=3x+3
3x=9
x=3 mph speed
4 mph to lake downhill*3 hours is 12 miles
2 mph back from lake uphill*6 hours is 12 miles
4 mph is the answer.</PRE>