Odpowiedź :
{2x - 3y = -18
{-x - y = -1 | * 2
{2x - 3y = -18
+ {-2x - 2y = -2
------------------------
-5y = -20 | : (-5)
y = 4
2x - 3 * 4 = -18
2x - 12 = -18
2x = -18 + 12
2x = -6 | : 2
x = -3
{2x - 3y = -18
{-x - y = -1 | * 2
{2x - 3y = -18
+ {-2x - 2y = -2
------------------------
-5y = -20 | : (-5)
y = 4
2x - 3 * 4 = -18
2x - 12 = -18
2x = -18 + 12
2x = -6 | : 2
x = -3