Решите систему неравенств 8-4x<=3; 4+6x<=20

\[\ \left\{ \begin{matrix} 8 - 4x \leq 3\ \ \\ 4 + 6x \leq 20 \\ \end{matrix} \right.\ \text{\ \ \ \ \ }\left\{ \begin{matrix} - 4x \leq - 5 \\ 6x \leq 16\ \ \ \ \\ \end{matrix} \right.\ \text{\ \ \ \ \ }\left\{ \begin{matrix} x \geq 1\frac{1}{4} \\ x \leq 2\frac{2}{3} \\ \end{matrix} \right.\ \]

\[Ответ:\ x \in \left\lbrack 1,25;\ \ 2\frac{2}{3} \right\rbrack\text{.\ }\]

\[\ |3x + 1| = 7\]

\[3x + 1 = 7\]

\[3x = 6\]

\[x = 2\]

\[3x + 1 = - 7\]

\[3x = - 8\]

\[x = - 2\frac{2}{3}\]

\[Ответ:x = 2\ \ и\ \ x = - 2\frac{2}{3}\text{.\ }\]