Помогите пожалуйста с номером 540 б) и г)

Question

Помогите пожалуйста с номером 540 б) и г)

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Answer 1

Б) =(15/21 - 14у/21) ·21=1            г)      7          2 ·4          1 · 3
     1у/21 ·21=1                                     -----m + --------m - -------m=7
         у=1                                                12          12          12
                                               
                                                              7m+8m-3m
                                                            -------------------=7
                                                                  12
                                                              
                                                                  12m
                                                                  ------=7
                                                                   12

                                                                    m=7