Question 808946
{{{5x+z=y}}} ------eqn. 1
{{{-y+2x=3=-z}}} ------eqn. 2
{{{3x+4y=18}}} ------eqn. 3


From eqn. 2,

{{{3=-z}}}
Therefore,
{{{z=-3}}}

Did you say "solve for z"?