Walk me through the steps on how to calculate the volume

Need this asap if anyone can i would be very grateful. if you could show workings that would really

Which number completes the inequality? 2/3 < _ < 7/9

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?