The solution is x = 2/129, y = 142/129, z = 23/129
That is the correct solution for what you posted. Are you
sure you copied it correctly? The fact that the answers came
out to be such unusual fractions is why I suspect you may not
have copied it correctly.
You also did not state what method for solving these you are
studying. There are many methods. Post again making sure you
copy the problem correctly, and that you tell what method for
solving systems of equation you are studying. Then we will
walk you through it, not just post the answer.