x-y-z=3 -x+2y+5z=-1 x+y+4z=4

x-y-z=3
-x+2y+5z=-1
x+y+4z=4

x-y-z=3
-x+2y+5z=-1
__________+
y+4z=2


x-y-z=3
x+y+4z=4
________-
-2y-5z=-1

y+4z=2 ==>y=2-4z
-2y-5z=-1
-2(2-4z)-5z=-1
-4+8z-5z=-1
3z =-1+4
z =3:3=1
y=2-4z
=2-4(1)
=-2
x-y-z=3
x-(-2)-1=3
x =3-1
x =2
Jadi x=2 y=-2 z=1