Here is how you would do this: If there are 1000 meters in one kilometer, and you know that this track is 200 meters long, then you can find how many times Julius must run around the track in order to reach ONE kilometer:
1000 meters / 200 meters = 5 times in around the track for ONE kilometer.
To find how many times Julius would need to run around to reach THREE kilometers you simply do the following:
5 x 3 = 15 ---> Julius would need to run around the track 15 times in order to reach 3 kilometers.