$\begin{equation*} \begin{cases} 2x - y = 2 &\\ 3x - 2y = 3 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} y = 2x - 2 &\\ 3x - 2y = 3 & \end{cases} \end{equation*}$
3x − 2 * (2x − 2) = 3
3x − 4x + 4 = 3
−x = 3 − 4
−x = −1
x = 1
y = 2x − 2 = 2 * 1 − 2 = 0
Ответ: (1;0)

$\begin{equation*} \begin{cases} 5y - x = 6 &\\ 3x - 4y = 4 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x = 5y - 6 &\\ 3x - 4y = 4 & \end{cases} \end{equation*}$
3 * (5y − 6) − 4y = 4
15y − 18 − 4y = 4
11y = 4 + 18
11y = 22
y = 22 : 11
y = 2
x = 5y − 6 = 5 * 2 − 6 = 10 − 6 = 4
Ответ: (4;2)

$\begin{equation*} \begin{cases} 3x + 4y = 55 &\\ 7x - y = 56 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 3x + 4y = 55 &\\ y = 7x - 56 & \end{cases} \end{equation*}$
3x + 4 * (7x − 56) = 55
3x + 28x − 224 = 55
31x = 55 + 224
31x = 279
x = 279 : 31
x = 9
y = 7x − 56 = 7 * 9 − 56 = 63 − 56 = 7
Ответ: (9;7)

$\begin{equation*} \begin{cases} 4y - x = 11 &\\ 6y - 2x = 13 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x = 4y - 11 &\\ 6y - 2x = 13 & \end{cases} \end{equation*}$
6y − 2 * (4y − 11) = 13
6y − 8y + 22 = 13
−2y = 13 − 22
−2y = −9
y = −9 : (−2)
y = 4,5
x = 4y − 11 = 4 * 4,5 − 11 = 18 − 11 = 7
Ответ: (7;4,5)