co 8 dong tien.trong do co 1 dong tien gia va 7 dong tien that.cac dong tien that co khoi luong bang nhau,dong tien gia nhe hon dong tien that.zay lam sao chi voi 2 lan can ma co the tim duoc dong tien gia(loai can co 2 dia can).nho cac bac tim giup em!