3 2 -2 15
2 -2 3 -3
4 -1 3 3
Swap: Row 1 and 2, and then 2 and 3.
2 -2 3 -3
4 -1 3 3
3 2 -2 15
R1/2 to R1
1 -1 3/2 -3/2
4 -1 3 3
3 2 -2 15
-4R1 + R2 to R2
1 -1 3/2 -3/2
0 3 -3 9
3 2 -2 15
R2/4 to R2
1 -1 3/2 -3/2
0 1 -1 3
3 2 -2 15
-3R1 + R3 to R3
1 -1 3/2 -3/2
0 1 -1 3
0 5 -13/2 39/2
-5R2 + R3 to R3
1 -1 3/2 -3/2
0 1 -1 3
0 0 -5 15
R3/-5 to R3
1 -1 3/2 -3/2
0 1 -1 3
0 0 1 -3
R3 + R2 to R2
1 -1 3/2 -3/2
0 1 0 0
0 0 1 -3
R2 + R1 to R1
1 0 3/2 -3/2
0 1 0 0
0 0 1 -3
-3/2*R3 + R1 to R1
1 0 0 3
0 1 0 0
0 0 1 -3
x = 3, y = 0, z = -3
John

Egw to Beta kai to Sigma
My calculator said it, I believe it, that settles it