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钢笔和铅笔共27盒，合计300支，钢笔每盒10支，铅笔每盒12支。钢笔和铅笔各有多少盒?小学生五年级列方程解决

设钢笔一共x盒，则铅笔为（27-X)盒。                                                  10x 12*(27-x)=300                                                                   10x 324-12x=300            -2x=-24                                                                           x=12                              ...全部

  设钢笔一共x盒，则铅笔为（27-X)盒。
                                                   10x 12*(27-x)=300                                                                   10x 324-12x=300            -2x=-24                                                                           x=12                                                                                27-12=15（盒）                                                                     答：钢笔有12盒，铅笔有15盒。收起