解：设聪聪原有X本，则明明原有（100-x）本.一起捐掉的=(4/9)x+(2/7)(100-x)剩下的=总共一起捐掉的=100-【(4/9)x+(2/7)(100-x)】=60解之得：X=72 100-x=28答：聪聪原有72本，明明原有28本。
