{x+3y=12
{14x+2y=-18
x=12-3y
14*(12-3y)+2y=-18
168-42y+2y=-18
168-40y=-18
-40y=-18-168
-40y=-186
y=-186/(-40)
y=4,65
x=12-3*4,65
x=12-13,95
x=-1,95
{x+3y=12
{14x+2y=-18
x=12-3y
14*(12-3y)+2y=-18
168-42y+2y=-18
168-40y=-18
-40y=-18-168
-40y=-186
y=-186/(-40)
y=4,65
x=12-3*4,65
x=12-13,95
x=-1,95