[tex]\displaystyle\\
\bold{-(-10 \sqrt{2} ):(-\sqrt{50})=- \frac{-10 \sqrt{2} }{-\sqrt{50}} =- \frac{10 \sqrt{2} }{\sqrt{50}} =}\\\\
\bold{= -\frac{10 \sqrt{2} }{\sqrt{25\times 2}} = -\frac{10 \sqrt{2} }{5\sqrt{2}}=-\frac{10 }{5}=} ~\boxed{\bold{-2}}[/tex]
