Compare the motion of two bowhead whales. Which bowhead whale was moving at a lower speed?

 - a bowhead whale that moved 50miles in 10hours
 - a bowhead whale that moved 20miles in 10hours
Look at the distance each bowhead whale moved and the time it took to move that distance.
One bowhead whale moved 20 miles in 10 hours.
The other bowhead whale moved 50 miles in 10 hours.
Notice that each bowhead whale spent the same amount of time moving. The bowhead whale that moved 20 miles moved a shorter distance in that time. So, that bowhead whale must have moved at a lower speed.