The area of a trapezium shaped field is 480m the distance between two parlel sides is 15m and one of the parrellel side is 20m find the other parralel side

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?