I need help as soon as posible pls

Two times a number plus three times another number equals 4. three times the first number plus four times the other number is 7. find the numbers

Find the domain of the following expression: 1/(√x)-2

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?