Question 65845
x + y + z = 5
x - 2y + z = 8
3x - y - z = 3
:
The problem lends itself the elimination method
Add the 1st and 3rd equations and find x:
x + y + z = 5
3x - y - z = 3
------------------add
4x + 0y + 0z = 8
x = 8/4
x = 2
:
Substitute 2 for x in the 2nd and 3rd equations
 2 - 2y + z = 8
3(2) -y - z = 3
:
2 - 2y + z = 8
6 - y -  z = 3
--------------- add
8 - 3y + 0z = 11
-3y = 11 - 8
y = 3/-3
y = -1
:
I'll let you find the value of z. Check solutions in the original equations.