[tex]\it \dfrac{24}{5\sqrt6}- \dfrac{12}{\sqrt6}+ \dfrac{21}{10\sqrt6}- \dfrac{28}{2\sqrt6}=\dfrac{1}{\sqrt6}\Big(\dfrac{24}{5}-12+\dfrac{21}{10}-\dfrac{28}{2}\Big)=\\ \\ \\ =\dfrac{1}{\sqrt6}(4,8-12+2,1-14)=\dfrac{-19,1}{\sqrt6}=-\dfrac{19,1\sqrt6}{6}=-\dfrac{191\sqrt6}{60}[/tex]
