x + y = 4 , x + z = 4, y + z = 4

Answer 1

1st - 2nd: y-z=0
y = z

2nd - 3rd: x-y=0
x = y

so x = y = z
so from 1st : 2x = 4
x = 2

so x = y = z = 2

Answer 2

x+y + 0z=4
x+0y+z=4
0x+y+z=4

1,1,0,4
1,0,1,4
0,1,1,4
http://www.gregthatcher.net//Mathematics/GaussJordan.aspx

all variables are equal to 2