\[y = \frac{3x - 1}{12 + 5x}\]
\[12 + 5x \neq 0\]
\[5x \neq - 12\]
\[x \neq - 2,4.\]
\[D(y) = ( - \infty; - 2,4) \cup ( - 2,4; + \infty).\]