Answer:
For 90 minutes of TV there will be 24 mins of commercials
Step-by-step explanation:
You start with 30 and keep adding 30 mins each time until you get to 90. (So..30..60..90) each time you add 30mins you add 8 more minutes to the commercials)
30 mins tv----8mins commercials
60 mins tv----16mins commercials
90 mins tv----24mins commercials
Hope this helps, good luck!