ba lop 6a,6b,6c chia nhau mot so but may dung trong 6 hop . So but dung trong 6 hop nhu sau : hop 1 co 31 cai but , hop 2 co 20 cai but, hop 3 co 19 cai but , hop 4 co 18 cai but , hop 5 co 16 cai but , hop 6 co 15 cai but . Hai lop 6a va 6b nhan duoc 5 hop va so but ma lop 6a nhan gap 2 lan so but cua lop 6b. Hoi moi lop nhan duoc bao nhieu cai but ??
Giai ra nhe !!!!