\[\frac{5x}{12} - \frac{x - 2}{4} + \frac{x + 1}{3} < 0\ \ \ \ \ | \cdot 12\]
\[5x - 3 \cdot (x - 2) + 4 \cdot (x + 1) < 0\]
\[5x - 3x + 6 + 4x + 4 < 0\]
\[6x < - 10\]
\[x < - \frac{10}{6}\]
\[x < - 1\frac{2}{3}\]
\[Ответ:x \in \left( - \infty;\ - 1\frac{2}{3} \right).\]