Answer:
21 minutes of commercials
Step-by-step explanation:
If Hits 96 must play 3 minutes of commercials for every 30 minutes of music played, than the ratio of minutes of commercials to minutes of music is 3:30=1:10.
If 210 minutes of music is played, we can model the situation with the equation 
We can use cross multiply to simplify the equation to 
Dividing each side by 10, we get
So, if 210 minutes of music is played, 21 minutes of commercials is played.