If 15 boys are in sports (3x), then x=5. Girls in sports = 2x = 10. Total students in sports = 15+10=25. Students not in sports = 60-25=35. Let boys not in sports be y, girls not in sports be y+5. So y + (y+5) = 35 -> 2y=30 -> y=15. Girls not in sports = 20. Total girls = 10 + 20 = 30. [cite: 1, 1773, 1781]