Hello could you please help me

When only separate discreet points are graphed it is called?

You are at a restaurant and owe $56.20 for your meal. you want to leave an 18% tip. approximately how much is your tip?

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?