Verified answer

[tex]\displaystyle\bf\ß\frac{25-m}{\sqrt{m}+5 }=\frac{5^{2}-(\sqrt{m})^{2} }{\sqrt{m} +5} =\frac{(5-\sqrt{m} )\cdot(5+\sqrt{m} )}{\sqrt{m} +5} =5-\sqrt{m}[/tex]