Answer:
seniors: 780
juniors: 1170
sophomores: 975
freshmen: 585
Explanation:
4 + 6 + 5 + 3 = 18
3510/18 = 195
195(4) = 780
195(6) = 1170
195(5) = 975
195(3) = 585
3.5m questions
4.5m answers