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