Question 136801
{{{z=x-y+4}}}
{{{z=y-w-3}}}
{{{z=w-x+5}}}


{{{z=x-y+4}}} => {{{x=z+y-4}}}, so


{{{z=w-x+5}}} => {{{z=w-(z+y-4)+5}}} => {{{2z = w-y+9}}}


{{{z=y-w-3}}} => {{{y=z+w+3}}}, so


{{{2z = w - (z+w+3) +9}}} => {{{2z=-z+6}}} => {{{3z=6}}} => {{{z=2}}}