{x-y=2
{2x-3y=-1
x=2+y
2(2+y)-3y=-1
4+2y-3y=-1
-y=-1-4
-y=-5|:(-1)
y=5
x-5=2
x=2+5
x=7
{-x+y=4
{4x+y=-1
y=4+x
4x+4+x=-1
5x=-1-4
5x=-5|:5
x=-1
-(-1)+y=4
y=4-1
y=3
{3x+y=4
{5x+y=10
y=4-3x
5x+4-3x=10
2x=10-4
2x=6|:2
x=3
3*3+y=4
y=4-9
y=-5
{8x-3y=7
{3x+y=9
y=9-3x
8x-3(9-3x)=7
8x+27+9x=7
17x=7-27
17x=-20|:17
x=-20/17
-20/17*3+y=9
y=9+60/17
y=12 9/17
{x+2y=-2
{0,5x-y=6
x=-2-2y
(-2-2y)0,5-y=6
-1-1-y=6
-y=6+2
-y=8|:(-1)
y=-8
x-8*2=2
x=2+16
x=18
{12x-y=18
{x+0,5y=5
x=5-0,5y
(5-0,5y)12-y=18
60-6y-y=18
-7y=18-60
-7y=-42|:(-7)
y=6
x+0,5*6=5
x=5-3
x=