2x+y=11
multiply by 2
4x+2y=22
z+2y=12
------
4x-z=10
------
z+2x=8
multiply by 2
4x+2z=16
4x-z=10
------
-3z=-6
z=2
x=3
y=5
so,,,
2x+3y+4z=29
multiply by 2
4x+2y=22
z+2y=12
------
4x-z=10
------
z+2x=8
multiply by 2
4x+2z=16
4x-z=10
------
-3z=-6
z=2
x=3
y=5
so,,,
2x+3y+4z=29