\[3x - 7 - (12x + 5) = - 3\]
\[3x - 7 - 12x - 5 = - 3\]
\[- 9x = - 3 + 12\]
\[- 9x = 9\]
\[x = - 1.\]
\[Ответ:при\ x = - 1.\]