一个三层书架,上层有书41本,中层比上层少6本,下层比中层多10本,下层有多少本书?9P2a2l'm9V0n/J9`
算式:提示9S*a1i4m,R7T+_;T3c8c/r9P2a2l'm9V0n/J9`
答:下层有;I:r)m2|5{)i'f2S)i4i9A本书。9P2a2l'm9V0n/J9`