[tex]\it \Big(\dfrac{5}{2\sqrt7}-\dfrac{2\sqrt7}{7}+\dfrac{3}{2\sqrt7}\Big):\dfrac{1}{\sqrt{14}}= \Big(\dfrac{8}{2\sqrt7}-\dfrac{2\sqrt7}{\sqrt7\cdot\sqrt7}}\Big):\dfrac{1}{\sqrt{14}}=\\ \\ \\ = \Big(\dfrac{4}{\sqrt7}-\dfrac{2}{\sqrt7}}\Big):\dfrac{1}{\sqrt{14}}=\dfrac{2}{\sqrt7}\cdot\dfrac{\sqrt{14}}{1}=2\sqrt{\dfrac{14}{7}}=2\sqrt2[/tex]
