помогите решить номер 5. а, б, в. Заранее спасибо!

x+18=22*3                                                      x-18=27/3

x+18=66                                                          x-18=9

x=66-18                                                           x=18+9

x=48                                                                 x=27

48+18=22*3                                                    27-18=27/3

 66=66                                                             9=9 

x-20=40*2

x-20=80

x=80+20

x=100

100-20=40*2

80=80