Goi x la so hoc sinh can tim
Ta co:(x-5) chai het cho 12,15,18 va x 200<x<400
=>(x-5) thuoc BC(12,15,18)
12=22.3 15=3.5 18=2.32
BCNN(12,15,18)=22.32.5=180
BC(12,15,18)={0,180,360,540,..}
Vi 200<x<400 nen x-5 thuoc 360
=>x-5=360
x =360+5=365
Vay so hoc sinh khoi 6 la 365 h/sinh
Mk viet dau khong duoc nen ban rang doc nha!!!