Bus A and Bus B leave the bus depot at 6 am.

Bus A takes 20 minutes to do its route and bus B takes 35 minutes to complete its route.

At what time are they both back at the bus depot together?

Give your answer as a 12-hour clock time

8.20 am

Step-by-step explanation:

First, we have that Bus A will be back after 20 minutes, then after 40, then 60, 80, 100, 120, 140, 160 minutes, etc.

Then, we have that Bus B will be back after 35 minutes, then 70, then 105, then 140, 175 ...

From the list above we see that the first time they are both back at the station is after 140 minutes. (it's the MCM).

If we express this in terms of minutes, since one hour has 60 minutes, 2 hours have 120 minutes and thus, 140 minutes is 2 hours and 20 minutes.

Therefore, they will be both back at the station 2 hours and 20 minutes after they first departed at 6 am, so they will be back at the depot at 8.20 am