I don't understand this ФωФ

: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?

An airplane travels at an unknown elevation before it descends 3 miles to an elevation of 15 miles. find the elevation of the plane before its descen.

Sue's average score for three bowling games was 162. in the second game, sue scored 10 less than in the first game. in the third game, she scored 13 less than in the second game. what was her score in the first game?