Question Number 20798 by ANTARES_VY last updated on 03/Sep/17
$$\begin{cases}{\mathrm{4}\boldsymbol{{x}}−\boldsymbol{{y}}=\mathrm{11}}\\{\mathrm{2}\boldsymbol{{y}}+\mathrm{5}\boldsymbol{{x}}=\mathrm{5}}\\{\boldsymbol{{x}}−\mathrm{2}\boldsymbol{{z}}=\mathrm{9}}\end{cases}\:\:\:\:\boldsymbol{{z}}+\boldsymbol{{y}}−\boldsymbol{{x}}=? \\ $$