There are 9 students in a class: 5 boys and 4 girls. if the teacher picks a group of 4 at random, what is the probability that everyone in the group is a boy?

Sarah took the advertising department from her company on a round trip to meet with a potential client. including sarah a total of 11 people took the trip. she was able to purchase coach tickets for $280 and first class tickets for $1280. she used her total budget for airfare for the trip, which was $6080. how many first class tickets did she buy? how many coach tickets did she buy?