$\begin{equation*} \begin{cases} 3(x - 5) - 1 = 6 - 2x &\\ 3(x - y) - 7y = -4 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 3x - 15 - 1 = 6 - 2x &\\ 3x - 3y - 7y = -4 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 3x + 2x = 6 + 15 + 1 &\\ 3x - 10y = -4 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 5x = 22 &\\ 3x - 10y = -4 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x = 4,4 &\\ 3x - 10y = -4 & \end{cases} \end{equation*}$
3 * 4,4 − 10y = −4
13,2 − 10y = −4
−10y = −13,2 − 4
−10y = −17,2
y = 1,72
Ответ: x = 4,4, y = 1,72.

$\begin{equation*} \begin{cases} 6(x + y) - y = -1 &\\ 7(y + 4) - (y + 2) = 0 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 6x + 6y - y = -1 &\\ 7y + 28 - y - 2 = 0 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 6x + 5y = -1 &\\ 6y + 26 = 0 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 6x + 5y = -1 &\\ 6y = -26 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 6x + 5y = -1 &\\ y = -\frac{13}{3} = -4\frac{1}{3} & \end{cases} \end{equation*}$
$6x + 5 * (-\frac{13}{3}) = -1$
$6x - \frac{65}{3} = -1$
$6x = -1 + \frac{65}{3}$
$6x = \frac{62}{3}$
$x = \frac{62}{3} : 6$
$x = \frac{62}{3} * \frac{1}{6}$
$x = \frac{31}{3} * \frac{1}{3}$
$x = \frac{31}{9} = 3\frac{4}{9}$
Ответ: $x = 3\frac{4}{9}, y = -4\frac{1}{3}$