Odpowiedź :
{4x + 5y = -4 / * (-7)
{6x + 7y = -6 / 5
{-28x - 35y = 28
+ {30x + 35y = -30
---------------------------
2x = -2 / : 2
x = -1
4 * (-1) + 5y = -4
-4 + 5y = -4
5y = -4 + 4
5y = 0 / : 5
y = 0
{-2x + 5y = -10 / * 4
{7x - 4y = 8 / * 5
{-8x + 20y = -40
+ {35x - 20y = 40
-------------------------
27x = 0 / : 27
x = 0
-2 * 0 + 5y = -10
0 + 5y = -10
5y = -10 / : 5
y = -2