Compare the motion of two mountain bikers. Which mountain biker was moving at a lower speed?

 - a mountain biker who moved 150miles in 10hours
 - a mountain biker who moved 170miles in 10hours
Look at the distance each mountain biker moved and the time it took to move that distance.
One mountain biker moved 150 miles in 10 hours.
The other mountain biker moved 170 miles in 10 hours.
Notice that each mountain biker spent the same amount of time moving. The mountain biker who moved 150 miles moved a shorter distance in that time. So, that mountain biker must have moved at a lower speed.