Answer:
We need to find the least common multiple (LCM) of 12 and 15 to determine when both channels will start commercial breaks at the same time.
The multiples of 12 are: 12, 24, 36, 48, 60, ...
The multiples of 15 are: 15, 30, 45, 60, ...
So, the LCM of 12 and 15 is 60.
This means that both channels will start commercial breaks at the same time after 60 minutes.
The movies started at 8 p.m., so both channels will start commercial breaks at 9 p.m.
Step-by-step explanation: