Bai 3 : Co hai quang sat : quang 1 chua 70% sat , quang 2 chua 40% sat . Nguoi ta tron mot luong quang loai 1 voi mot luong quang loai 2 thi duoc hon hop quang chua 60% sat . Neu lay tang hon luc dau 5 tan quang loai 1 va lay giam hon luc dau 5 tan quang loai 2 thi duoc hon hop quang chua 65% sat . Tinh khoi luong moi loai quang dem tron luc dau ?
