Compare the motion of three cars. Which car was moving at the lowest speed?

 - a car that moved 210miles west in 5hours
 - a car that moved 160miles north in 5hours
 - a car that moved 225miles south in 5hours
Look at the distance each car moved and the time it took to move that distance. The direction each car moved does not affect its speed.
Notice that each car moved for 5 hours. The car that moved 160 miles moved the shortest distance in that time. So, that car must have moved at the lowest speed.