What is the boats speed in calm water? How far did the boat travel one way?
d r t downstream d b + 3 3 upstream d b 3 4 total 2d — 7 (It may turn out that I won’t need the “total” row.) I have used “b” to indicate the boat’s speed. Why are the rates “b + 3” and “b 3”? Because I actually have two speeds combined into one on each trip. The boat has a certain speed (the “speed in calm water” that I’m looking for; this is the speed that registers on the speedometer), and the water has a certain speed (this is the “current”). When the boat is going with the current, the water’s speed is added to the boat’s speed. This makes sense, if you think about it: even if you cut the engine, the boat would still be moving, because the water would be carrying it downstream. When the boat is going against the current, the water’s speed is subtracted from the boat’s speed. This makes sense, too: if the water is going fast enough, the boat will still be going downstream (a “negative” speed, because the boat would be going backwards at this point), because the water is more powe
