\(=\sqrt{18\left(4-\sqrt{15}\right)}-3\left(2-\sqrt{3}\right)-3\sqrt{5}\)
\(=\sqrt{9\cdot\left(8-2\sqrt{15}\right)}-6+3\sqrt{3}-3\sqrt{5}\)
\(=3\cdot\left(\sqrt{5}-\sqrt{3}\right)-6+3\sqrt{3}-3\sqrt{5}\)
\(=3\sqrt{5}-3\sqrt{3}-6+3\sqrt{3}-3\sqrt{5}\)
=-6