36) \((\sqrt{20}+\sqrt{5})\cdot\sqrt{5}\)

\(\sqrt{20}=2\sqrt{5}\).

\((\sqrt{20}+\sqrt{5})\sqrt{5}=(2\sqrt{5}+\sqrt{5})\sqrt{5}=3\sqrt{5}\cdot\sqrt{5}=15\).

Ответ: 15