Odpowiedź :
[tex]\\\begin{cases}x-3y+9x=3x-4\\ 2(2x-y)=4 /:2\end{cases} \\\begin{cases}10x-3x-3y=-4\\2x-y=2\implies y=2x-2 \end{cases} \\7x-3(2x-2)=-4 \\7x-6x+6=-4 \\x=-4-6=-10 \\y=2*(-10)-2=-22 \\Odp. \begin{cases}x=-10\\y=-22\end{cases}[/tex]
x - 3(y - 3x) = 3x - 4
2(2x - y) = 4 /:2
x - 3y + 9x = 3x - 4
2x - y = 2
10x - 3x - 3y = -4
2x - y = 2
7x - 3y = -4
y = 2x - 2
7x - 3(2x - 2) = -4
7x - 6x + 6 = -4
x = -4 -6
x = -10
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y = 2*(-10) -2
y = -22
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{x = -10}
{y = -22}