Answer:
Mark is going on a run and went 10 meters in 20 seconds. He then kept going for another 20 meters and had been running for 20 seconds. He then started to run faster and in 20 more seconds he had ran 30 meters. He then was tired and started to slow down and in 40 seconds he ran 40 meters.
Explanation:
Not sure if this is want you wanted :)
