Bon ban chung tien mua mot qua bong. Hai gop mot nua so tien mua bong. So tien cua Binh gop ban 1/3 toan bo so tien gop cua cac ban khac. So tien cua Giang gop bang 1/4 so tien cua cac ban khac. Duong gop 2500 dong thi vua du so tien mua bong . Hoi bon ban da mua qua bong bao nhieu dong ?