Решите Систему Уравнений

1)
$3x + 4y = 0 \\ 2 x + 3y = 0 \\ \\ 3x + 4y = 0 \\ - 3x - 4.5y = - 1.5 \\ \\ - 0.5y = - 1.5 \\ y = 3 \\ x = - 4$

2)
$7x + 2y = 0 \\ 4y + 9x = 10 \\ \\ 14x + 4y = 0 \\ 9x + 4y = 10 \\ \\ 5x = - 10 \\ x = - 2 \\ y = 7$

3)
$5x + 6y = - 20 \\ 9y + 2x = 25 \\ \\ - 7.5x - 9y = 30 \\ 9y + 2x = 25 \\ \\ - 5.5x = 55 \\ x = - 10 \\ y = 5$

4)
$3x + 1 = 8y \\ 11y - 3x = - 11 \\ \\ 3x - 8y = - 1 \\ - 3x + 11y = - 11 \\ \\ 3y = - 12 \\ y = - 4 \\ x = - 11$