The number of students in three sections of Grade 10 in a school are in the proportion 3 ∶ 5 ∶ 8. If 15, 30 and 15 more students are admitted in the three sections, respectively, the new proportion becomes 4 ∶ 7 ∶ 9. The total number of students before the new admissions is:
1
240
2
160
3
320
4
400