Jada works a 5 hour work shift or 300 minutes at a retail store she gets a 15 minute break during her work shift what percent of jada work shift is her break

Mrs. morton has a special reward system for her class. when all her students behave well, she rewards them by putting 3 marbles into a marble jar. when the jar has 100 or more marbles, the students have a party. right now, the the jar has 24 marbles. how could mrs. morton reward the class in order for the students to have a party?