Compare the motion of two ducks. Which duck was moving at a lower speed?

 - a duck that moved 580miles in 10hours
 - a duck that moved 620miles in 10hours
Look at the distance each duck moved and the time it took to move that distance.
One duck moved 580 miles in 10 hours.
The other duck moved 620 miles in 10 hours.
Notice that each duck spent the same amount of time moving. The duck that moved 580 miles moved a shorter distance in that time. So, that duck must have moved at a lower speed.