mohon bantuannya! yg jago matematika tentang persamaan linear 3 variabel

x - y + 2z = -5
2x + y + z = -1
x + y - z = 3

2x + y + z = -1
x + y - z = 3
x + 2z = -4

x-y+2z = -5
x+2z = -4
-y = -1
y = 1

x-1+2z = -5
x+2z = -4

2x+1+z = -1
2x + z = -2

x+2z = -4
2x + z = -2

2x + 4z = -8
2x + z = -2
3z = -6
z = -2

x + 2(-3) = -4
x - 6 = -4
x = 2

maka HP X,Y,Z {2,1,-2}