Your answer works for the first equation, but for the second:
Check your matrix in RRF, it doesn't look right....
2x+3y-z=4 converting this into an augmented matrix and into echelon form
4x-2y+3z=-7
-6x+7y-7y=3
=
[1 1.5 -.5 2]
[0 1 -.8 2.2]
[0 0 1 8.9]
the answer i got was x= -7.5 y=9.3 z= 8.9
anyone care to solve this and check my answer?
many thanks!