Compare the motion of three sailboats. Which sailboat was moving at the lowest speed?

 - a sailboat that moved 50kilometers north in 5hours
 - a sailboat that moved 70kilometers west in 5hours
 - a sailboat that moved 25kilometers east in 5hours
Look at the distance each sailboat moved and the time it took to move that distance. The direction each sailboat moved does not affect its speed.
Notice that each sailboat moved for 5 hours. The sailboat that moved 25 kilometers moved the shortest distance in that time. So, that sailboat must have moved at the lowest speed.