(12x-7*(x+4)\7=(26-4x)\7
(12х-7х-28)*7=(26-4х)*7
(5х-28)*7=(26-4х)*7
35х-196=182-28х
35х+28х=182+196
63х=378
х=378/63
х=6
Проверим: (12*6-7*(6+4)\7=(26-4*6)\7
(72-42-28)/7=(26-24)/7
2/7=2/7
(12x-7*(x+4)\7=(26-4x)\7
(12х-7х-28)*7=(26-4х)*7
(5х-28)*7=(26-4х)*7
35х-196=182-28х
35х+28х=182+196
63х=378
х=378/63
х=6
Проверим: (12*6-7*(6+4)\7=(26-4*6)\7
(72-42-28)/7=(26-24)/7
2/7=2/7