Question 470271
Let the rate of the current be x miles per hour.The speed of the canoe  downstream will be: 6-x, and upstream 2+x.Since the rate of the current does not change we write: 6-x=2+x, solving this equation we get x=2 miles per hour, is the  rate of change of the current.
Answer:On still water the canoe travel 6-2=4 or 2+2=4 miles per hour, and the rate of the current is 2 miles/h.