1. The problem statement, all variables and given/known data Two boats start together and race across a 42 km wide lake and back. Boat A goes across at 42 km/h and returns at 42 km/h. Boat B goes across at 21 km/h, and its crew, realizing how far behind it is getting, returns at 63 km/h. Turnaround times are negligible, and the boat that completes the round-trip first wins. Which boat wins and by how much(km)? 2. Relevant equations Conversions Average Speed = Total distance/total time 3. The attempt at a solution I took 42km/h * 1h/84km = 1/2h for boat A to travel there and 1/2 h to travel back. 21km/h * 1h/84km = 1/4h for boat B to travel there leaving it 3/4h to travel back. Next I took the speed and multiplied by the hours: 42km/h * 1/4h = 10.5 km 21km/h * 1/4h = 5.25 km 63km/h * 3/4h = 47.25 km Then added the distance of boat B and subtracted boat A: (47.25km + 5.25km) - (10.5km + 10.5km) = 31.5km What am I doing wrong??