a) 74. (x-3)=0                        b) 71-(33+x) =26                          c) 12 : (3x-7) + 34=40

           x-3 =74.0                              33+x = 71-26                        12 : (3x-7)         = 40 - 34

           x-3 = 0                                  33+ x = 45                             12 : (3x-7)         = 6

           x     = 0+3                                    x = 45-33                               (3x-7)         = 12 : 6

           x     = 3                                        x = 12                                      3x-7          = 2  

   Vậy x=3                                           Vậy x= 12                                     3x             = 7 + 2

                                                                                                                3x              = 9

                                                                                                                 x               = 9 : 3

                                                                                                                  x               = 3

                                                                                                                   Vậy x = 3

d) x - 36 : 18 = 12                  c) 97- (64-x) = 44                       f) 101 + (105 : x-12).7 = 122

    x - 2          = 12                             64-x  = 97-44                               (105 : x-12).7  = 122-101

    x                = 12 + 2                      64-x    = 53                                   (105 : x-12).7  = 21

    x                = 14                                  x    = 64-53                              (105 : x-12)     = 21 : 7

Vậy x = 14                                              x     = 11                                     105 : x-12     = 3

                                                            Vậy x= 11                                      105 : x           = 3 + 12

                                                                                                                  105 : x           = 15    

                                                                                                                          x            = 105 : 15

                                                                                                                          x            =  7

                                                                                                                     Vậy x = 7