$\begin{equation*} \begin{cases} \frac{x}{3} - \frac{y}{2} = -4 |*6 &\\ \frac{x}{2} + \frac{y}{2} = -2 |*2 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 2x - 3y = -24 &\\ x + y = -4 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 2x - 3y = -24 &\\ y = -x - 4 & \end{cases} \end{equation*}$
2x − 3(−x − 4) = −24
2x + 3x + 12 = −24
5x = −24 − 12
5x = −36
x = −7,2
y = −(−7,2) − 4 = 7,2 − 4 = 3,2
Ответ: x = −7,2, y = 3,2.

$\begin{equation*} \begin{cases} \frac{a}{6} - 2b = 6 |*6 &\\ -3a + \frac{b}{2} = -37 |*2 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} a - 12b = 36 &\\ -6a + b = -74 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} a = 12b + 36 &\\ -6a + b = -74 & \end{cases} \end{equation*}$
−6(12b + 36) + b = −74
−72b − 216 + b = −74
−71b = −74 + 216
−71b = 142
b = −2
a = 12 * (−2) + 36 = −24 + 36 = 12
Ответ: a = 12, b = −2.

$\begin{equation*} \begin{cases} \frac{2m}{5} + \frac{n}{3} = 1 |*15 &\\ \frac{m}{10} - \frac{7n}{6} = 4 |*30 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 6m + 5n = 15 &\\ 3m - 35n = 120 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 5n = 15 - 6m &\\ 3m - 35n = 120 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} n = 3 - 1,2m &\\ 3m - 35n = 120 & \end{cases} \end{equation*}$
3m − 35(3 − 1,2m) = 120
3m − 105 + 42m = 120
45m = 120 + 105
45m = 225
m = 5
n = 3 − 1,2 * 5 = 3 − 6 = −3
Ответ: m = 5, n = −3.

$\begin{equation*} \begin{cases} 7x - \frac{3y}{5} = -4 |*5 &\\ x + \frac{2y}{5} = -3 |*5 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 35x - 3y = -20 &\\ 5x + 2y = -15 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 35x - 3y = -20 &\\ 2y = -15 - 5x & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 35x - 3y = -20 &\\ y = -7,5 - 2,5x & \end{cases} \end{equation*}$
35x − 3(−7,5 − 2,5x) = −20
35x + 22,5 + 7,5x = −20
42,5x = −20 − 22,5
42,5x = −42,5
x = −1
y = −7,5 − 2,5 * (−1) = −7,5 + 2,5 = −5
Ответ: x = −1, y = −5.