Ban Hien lam mot cai hop dang hinh hop chu nhat bang bia co chieu dai 25cm, chieu rong 12cm va chieu cao 10cm.
a) Tinh the tich cai hop do .
b) Neu dan giay mau tat ca cac mat ngoai cua hop do thi ban Hien can dung bao nhieu xang-ti-met vuong giay mau?