设每个甲、乙纸箱分别装x,(x+20)本教科书．960/x=960/(x+20)+8x=40或x=-60(舍）每个甲、乙纸箱分别装40，60本教科书
设甲纸箱可装x本教科书，乙纸箱可装y本教科书960/x = 960/y + 8y = x + 20解得x=40 y=60
