Subtract 2(first equation) from the second, and 3(first equation) from the third to eliminate x :
(2x + 3y + z) - 2(x + y + z) = 16 - 2*9
y - z = -2
(3x - 4y + 2z) - 3(x + y + z) = 1 - 3*9
-7y - z = -26
Now subtract either equation with y and z from the other to eliminate z. If we take the first from the second, we get
(-7y - z) - (y - z) = -26 - (-2)
-8y = -24
y = 3
Then
y - z = 3 - z = -2
z = 5
And lastly,
x + y + z = x + 3 + 5 = 9
x = 1
