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

 - a fish that moved 15miles in 5hours
 - a fish that moved 20miles in 5hours
Look at the distance each fish moved and the time it took to move that distance.
One fish moved 20 miles in 5 hours.
The other fish moved 15 miles in 5 hours.
Notice that each fish spent the same amount of time moving. The fish that moved 20 miles moved a farther distance in that time. So, that fish must have moved at a higher speed.