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

 - a car that moved 255miles west in 10hours
 - a car that moved 270miles south in 10hours
 - a car that moved 305miles north in 10hours
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 10 hours. The car that moved 305 miles moved the farthest distance in that time. So, that car must have moved at the highest speed.