@-)oi ! to chua hoc bai nay,sorry!vi khong giup duoc cau rui,sao ma hoc nhanh the co chu ,to cung co bai muon hoi ne .vay cau tra loi gium to y 2 cua cau 3 tr121 duoc ko nhanh len nhe ....neu co ai vao trang nay giai gium to luon nhe .to xin da ta .da ta