<PRE><B>Question 198623</B>
 x + 2y - z = 3
2x - y  + z = 3
3x -4y + 2z = -1
:
Multiply the 1st equation by 2, add to the 3rd equation
2x + 4y - 2z = 6
3x - 4y + 2z = -1
--------------------Addition eliminates y and z, find x:
5x = 5
x = 1
:
Replace x with 1 in the first two equations 
 1  + 2y - z = 3
2(1) - y + z = 3
:
2y - z = 3 - 1
-y + z = 3 - 2
:
2y - z = 2
-y + z = 1
--------------addition eliminates z, find y
y = 3
:
Use the 3rd equation to find z:
3x -4y + 2z = -1
3(1) - 4(3) + 2z = -1
3 - 12 + 2z = -1
-9 + 2z = -1
2z = -1 + 9
2z = 8
z = 4
:
:
Check solutions in the 2nd equation; x = 1; y = 3; z = 4
2x - y  + z = 3
2(1) - 3 + 4 = 3
2 - 3 + 4 = 3</PRE>