[tex]=( \frac{ \sqrt{3} }{2}- \frac{5 \sqrt{6} }{3} ):( \frac{2 \sqrt{6} }{10} - \frac{ \sqrt{6} }{6} )= \\ = \frac{ 3\sqrt{3} -10 \sqrt{6} }{6} : \frac{12 \sqrt{6}- 10\sqrt{6} }{60} = \\ = \frac{3\sqrt{3} -10 \sqrt{6}}{6}: \frac{ \sqrt{6} }{30} = \\ \\ = \frac{3\sqrt{3} -10 \sqrt{6}}{1} * \frac{5}{ \sqrt{6} }= \frac{15 \sqrt{3}- 50\sqrt{6} }{ \sqrt{6} } [/tex]