I have to use Gauss-Jordan elimination, put in reduced row echelon form and find all solutions to the following system of equations

2x - 3y - 8z = 7

-2x + 2z - w = -7

x - y - 3z + w = 6

I end up in RRE form

1 0 -1 0 | 3

0 1 2 0 | -1

0 0 0 1 | 3

I think

x = 3 + z

y = -1 - 2z

z = ???

w = 3

How can I solve the system?