co 3 kho hang A,B,C chua 1 so gao. Neu nhap vao kho A them 1/7 so gao cua kho do, xuat o kho B 1/9 so gao o kho do, xuat o kho C 2/7 so gao o kho do. Khi do so gao cua 3 kho bang nhau. Tinh so gao o moi kho biet luc ban dau kho B nhieu hon kho A la 20 ta gao