x+y=1 (a)
2x-y+z=1 (b)
x+2y+z=8/3 (c)
Eliminate 1 variable:
subtract b to c:
x+2y+z=8/3 (c)
-
2x-y+z=1 (b)
_________
-x+3y = 5/3 (1)
(a) and (1)
x+y=1
-x+3y= 5/3
Add both_
x+y=1
+
-x+3y= 5/3
_________
4y=8/3
y= (8/3 )/4
y= 2/3
Replace y on (a)
x+2/3=1
x=1-2/3
x= 1/3
Replace x and y on b
2x-y+z=1
2(1/3)-2/3+z=1
2/3-2/3 +z=1
z=1
