5x+6y=-2
10x+3y=-7
(x2) 10x+12y=-4
10x+3y=-7
10x-10x+12y-3y=-4+7
9y=3
y=3
10x + 3(3) = -7
y = 3
10x + 9 = -7
y = 3
10x = 16
y = 3
x = 8/5
y = 3
S={(8,5;3)}
5x + 4y = 13
2x - 7y = 31
(x2) 10x + 8y = 26
(x5) 10x -35y = 155
10x-10x+8y+35y=26-155
43y=-129
y=-3
5x + 4(-3) = 13
y=-3
5x -12 = 13
y = -3
5x = 25
y = -3
x = 5
y = -3
S={(5;-3)}