First, you would have to convert the kilometers to meters. So, each kilometer is 1000 meters, so you would have to multiply 4.2 and 1000. That gets you to 4200 meters. Since the question is asking you to estimate, I would round 4200 to 4000 and 325 to 300. Because Jason ran 325 meters farther than Kim, you would add 300 and 4000 to get 4300 meters.
*Answer: Jason ran about 4,300 meters.*