.
$\displaystyle \frac{4}{1-\sqrt{3}} - \frac{1}{\sqrt{3}}$
like in the image rationalize then
$\displaystyle \frac{4+4\sqrt{3}}{-2}-\frac{\sqrt{3}}{3}$
get the lcd which is $\displaystyle 6$
$\displaystyle \frac{-12-12\sqrt{3}-2\sqrt{3}}{6}$
$\displaystyle \frac{-12-14\sqrt{3}}{6}$
$\displaystyle -2- \frac{7\sqrt{3}}{3}$