1 be boi dang hinh hop chu nhat co chieu dai 50m , chieu rong 30 m chieu cao 3m . hoi can bao nhieu vien gach men hinh chu nhat co chieu rong 20cm va chieu dai 25cm de lat kin phan ben trong be boi noi tren ? Biet rang dien tih cac mach vua khong dang ke