Three times the sum of a number and six

The pyramid below was dissected by a horizontal plane which shape describes the pyramid horizontal cross section

:24% of students in a class are girls. if there are less than 30 students in this class, how many students are there? how many girls are there?

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?