If each student needs 7 balloons, that would depend on the number of students in question. This can be answered with simple multiplication.
7 balloons x 1 student = 7 balloons
7 balloons x 2 students = 14 ballons
7 balloons x 3 students = 21 ballons
7 balloons x 4 students = 28 ballons
Etc, etc
