$\begin{equation*} \begin{cases} 4x - 5y = 1 &\\ 2x - 3y = 2 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 4x - 5y = 1 &\\ 2x = 2 + 3y & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 4x - 5y = 1 &\\ x = 1 + 1,5y & \end{cases} \end{equation*}$
4x − 5y = 1
4 * (1 + 1,5y) − 5y = 1
4 + 6y − 5y = 1
y = 1 − 4
y = −3
x = 1 + 1,5y = 1 + 1,5 * (−3) = 1 − 4,5 = −3,5
Ответ: (−3,5;−3)

$\begin{equation*} \begin{cases} 3x + 4y = 0 &\\ 2x + 3y = 1 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 3x + 4y = 0 &\\ 2x = 1 - 3y & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 3x + 4y = 0 &\\ x = 0,5 - 1,5y & \end{cases} \end{equation*}$
3x + 4y = 0
3 * (0,5 − 1,5y) + 4y = 0
1,5 − 4,5y + 4y = 0
−0,5y = −1,5
y = −1,5 : (−0,5)
y = 3
x = 0,5 − 1,5y = 0,5 − 1,5 * 3 = 0,5 − 4,5 = −4
Ответ: (−4;3)

$\begin{equation*} \begin{cases} 4x - 3y = 7 &\\ 5x + 2y = 26 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 4x - 3y = 7 &\\ 2y = 26 - 5x & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 4x - 3y = 7 &\\ y = 13 - 2,5x & \end{cases} \end{equation*}$
4x − 3y = 7
4x − 3 * (13 − 2,5x) = 7
4x − 39 + 7,5x = 7
11,5x = 7 + 39
11,5x = 46
x = 46 : 11,5
x = 4
y = 13 − 2,5x = 13 − 2,5 * 4 = 13 − 10 = 3
Ответ: (4;3)

$\begin{equation*} \begin{cases} 3x - 5y = 0 &\\ 8y - 5x = -1 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 5y = 3x &\\ 8y - 5x = -1 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} y = 3x : 5 &\\ 8y - 5x = -1 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} y = 0,6x &\\ 8y - 5x = -1 & \end{cases} \end{equation*}$
8y − 5x = −1
8 * 0,6x − 5x = −1
4,8x − 5x = −1
−0,2x = −1
x = −1 : (−0,2)
x = 5
y = 0,6x = 0,6 * 5 = 3
Ответ: (5;3)