Two people are jogging around a circular track in the same direction. One person can go completely around the track in 21 minutes. The second person takes 45 minutes. If they both start running in the same place at the same time, how long will it take them to be together at this place if they continue to run?

After 315 minutes both person will be together

Explanation:

We have given that first person takes 21 minutes to complete the one round and second person takes 45 minutes to complete the one round

We have to find the time at which both person will be together

That time will be equal to LCM of both time

That is LCM of 21 and 45

Factor of 21 = 3*7

Factor of 45 = 3*3*5

So LCM will be 3*3*5*7=315 minutes

So after 315 minutes both person will be together