\[1 - \frac{x}{3} = \frac{2x + 6}{3}\ \ \ \ \ \ \ | \cdot 3\]
\[3 - x = 2x + 6\]
\[- x - 2x = 6 - 3\]
\[- 3x = 3\]
\[x = - 1.\]
\[Ответ:x = - 1.\]