To find out when the red line and green line trains will next arrive at the station at the same time, you can determine the least common multiple (LCM) of their arrival times.
The red line arrives every 6 minutes, and the green line arrives every 8 minutes. To find the LCM of 6 and 8:
1. List the multiples of 6: 6, 12, 18, 24, 30, ...
2. List the multiples of 8: 8, 16, 24, 32, 40, ...
The least common multiple they share is 24 minutes. So, the red line and green line trains will next arrive at the station at the same time in 24 minutes.