Bai 5:
Goi so to la a(a thuoc N*)
60:a,72:a=>a thuoc UCLN(60,72)
Ta co :
60=2^2.3.5
72=2^3.3^2
UCLN(60,72)=2^2.3=12
Moi to co so hoc sinh nam la:
     60:12=5( ban)
Moi to co so hoc sinh nu la :
      72:12=6( ban )
Vay: co the chia thanh 12 to,moi to co 5 nam,6 nu