$$2 x ^ { 2 } - 4 y ^ { 2 } = 50 \quad , \quad x + y = 6$$
$x=\sqrt{47}+12\approx 18.8556546\text{, }y=-\left(\sqrt{47}+6\right)\approx -12.8556546$
$x=12-\sqrt{47}\approx 5.1443454\text{, }y=\sqrt{47}-6\approx 0.8556546$