[tex]\it \dfrac{\sqrt3}{3}-\dfrac{5}{\sqrt3}=\dfrac{\sqrt3}{\sqrt3\cdot\sqrt3}-\dfrac{5}{\sqrt3}=\dfrac{1}{\sqrt3}-\dfrac{5}{\sqrt3}=\dfrac{1-5}{\sqrt3}=-\dfrac{^\sqrt3)4}{\sqrt3}=-\dfrac{4\sqrt3}{3}[/tex]
