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

 - a fish that moved 5kilometers in 10hours
 - a fish that moved 30kilometers in 10hours
Look at the distance each fish moved and the time it took to move that distance.
One fish moved 5 kilometers in 10 hours.
The other fish moved 30 kilometers in 10 hours.
Notice that each fish spent the same amount of time moving. The fish that moved 5 kilometers moved a shorter distance in that time. So, that fish must have moved at a lower speed.