\[y = kx + b;\ \ A\ ( - 2;11);\ \ B\ (12;4).\]
\[\left\{ \begin{matrix}
11 = - 2k + b\ \ \ (1) \\
4 = 12k + b\ \ \ \ \ \ (2) \\
\end{matrix} \right.\ \]
\[(1) - (2):\]
\[7 = - 14k\ \]
\[k = - \frac{1}{2}.\]
\[\left\{ \begin{matrix}
k = - \frac{1}{2}\text{\ \ \ \ \ \ \ } \\
b = 4 - 12k \\
\end{matrix} \right.\ \text{\ \ \ \ \ \ \ }\left\{ \begin{matrix}
k = - \frac{1}{2}\text{\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ } \\
b = 4 - 12 \cdot \left( - \frac{1}{2} \right) \\
\end{matrix} \right.\ \text{\ \ \ \ \ }\]
\[\left\{ \begin{matrix}
k = - \frac{1}{2}\text{\ \ \ } \\
b = 4 + 6 \\
\end{matrix} \right.\ \text{\ \ \ \ }\left\{ \begin{matrix}
k = - \frac{1}{2} \\
b = 10\ \\
\end{matrix} \right.\ \]
\[Уравнение\ прямой:\ \]
\[y = - 0,5x + 10.\]