\(\sqrt{32}+\sqrt{200}=\sqrt{16}⋅\sqrt{2}+\sqrt{100}⋅\sqrt{2}=4\sqrt{2}+10\sqrt{2}\text{.}\)

\(4\sqrt{2}+10\sqrt{2}=14\sqrt{2}\text{.}\)

\(\sqrt{20}=\sqrt{4}⋅\sqrt{5}=2\sqrt{5}\text{.}\)

\(7\sqrt{28}=7⋅\sqrt{4}⋅\sqrt{7}=7⋅2⋅\sqrt{7}=14\sqrt{7}\text{.}\)

\(4\sqrt{80}-3\sqrt{125}=4⋅\sqrt{16}⋅\sqrt{5}-3⋅\sqrt{25}⋅\sqrt{5}\text{.}\)

\(4⋅4⋅\sqrt{5}-3⋅5⋅\sqrt{5}=16\sqrt{5}-15\sqrt{5}=1\sqrt{5}\text{.}\)

\(\sqrt{\frac{81}{100}}={\sqrt{81} \over \sqrt{100}}=\frac{9}{10}\text{.}\)