After jackson plays for 9 min his mom tells him he has used up 30% of his time. how many more min can he play?

You can use this method: part = percent •whole.
Your percent is .30 and your part is 9.
9=.3x
You now divide 9 by .3 which is 30. His total time is 30 minutes. Now you need to subtract how many minutes be played already from his total play time. 30 - 9 would be 21. He has 21 more minutes to play.