 akaev1087 
                                                08.04.2020 07:51
                                                
                                                akaev1087 
                                                08.04.2020 07:51
                                             Fanapav 
                                                08.04.2020 07:51
                                                
                                                Fanapav 
                                                08.04.2020 07:51
                                             Кологривко 
                                                08.04.2020 07:51
                                                
                                                Кологривко 
                                                08.04.2020 07:51
                                             LumpySpacePrincess01 
                                                08.04.2020 07:51
                                                
                                                LumpySpacePrincess01 
                                                08.04.2020 07:51
                                             olgaerchik 
                                                08.04.2020 07:50
                                                
                                                olgaerchik 
                                                08.04.2020 07:50
                                             666555y67767676 
                                                08.04.2020 07:50
                                                
                                                666555y67767676 
                                                08.04.2020 07:50
                                             Saxarok2018 
                                                04.12.2020 10:43
                                                
                                                Saxarok2018 
                                                04.12.2020 10:43
                                             Albina1967 
                                                04.12.2020 10:43
                                                
                                                Albina1967 
                                                04.12.2020 10:43
                                            
х = 9+d
y = x+d = 9+2d
z = y+d = 9+3d
13 = z+d = 9+4d ---> d = 1
x = 10
y = 11
z = 12