1. The problem statement, all variables and given/known data The concentration c of fish away from a feeding point in a lake is given by c(x,y) = 1/(x2 + y2). Find the total change of fish concentration detected by an observer riding a boat traveling with a speed u = 10 m/s straight away from the feeding point. What is the corresponding change detected by a stationary observer. 2. Relevant equations 3. The attempt at a solution Can someone give me how to start solving this problem. I'm having trouble making a start at it.