To increase an amount by 12.5% what single multiplier would you use

Given the graphed function below which of the following orders pairs are found on the inverse function

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?

Will give a: 122 b: 90 c: 48 d: 180