x + y + z - 3 = 0
2x + 3y - z = 0
x - y + 3z - 7 = 0
x+y+z-3=0
2x+3y-z=0
x-y+3z-7=0
z=2x+3y
x+y+2x+3y-3=0
x-y+6x+9y-7=0
3x+4y-3=0
7x+8y-7=0
6x+8y=6
7x+8y=7
x=1
y=0
z=2