Square both sides: $\displaystyle{{\left(\sqrt{{{x}-{5}}}\right)}}^{{2}}={{\left(-{5}\right)}}^{{2}}\usepackage{cmbright}\Huge\$

Simplify: $\displaystyle{x}-{5}={25}\usepackage{cmbright}\Huge\$

Solve for x: $\displaystyle{x}={30}\usepackage{cmbright}\Huge\$

Check: $\displaystyle\sqrt{{{30}-{5}}}=-{5}\usepackage{cmbright}\Huge\$ ? $\displaystyle\sqrt{{{25}}}\ne-{5}\usepackage{cmbright}\Huge\$ extraneous solution

Therefore, there is no solution.