1. The problem statement, all variables and given/known data A boat leaves a dock at 2:00 pm and travels due south at a speed of 20 km/h. Another boat has been heading due east at 15 km/h and reaches the same dock at 3:00 pm. At what time were the two boats closest together? 3. The attempt at a solution[/b We actually don't need to use integrals for this(and we haven't really learned how), but I want to. So a couple of quick questions... first, integrating 20 equals 20t+c correct? and second, either the 15km/h or the 20km/h should be negative, and it doesn't matter which one, right? If those two things are true, I should be all set, if not, I might have more questions. :p Thanks a lot for the help guys.