[tex] \frac{ \sqrt{3}-3 }{2} - \frac{1}{ \sqrt{3}+1 } = \\ \\ =\frac{ (\sqrt{3}-3)(\sqrt{3}+1) }{2(\sqrt{3}+1)} - \frac{1*2}{ 2(\sqrt{3}+1) }= \\ \\ =\frac{ (\sqrt{3}-3)(\sqrt{3}+1)-2 }{2(\sqrt{3}+1)}= \\ \\ = \frac{3-3\sqrt{3}+\sqrt{3}-3-2 }{2(\sqrt{3}+1)}= \\ \\ =\frac{-2\sqrt{3}-2 }{2(\sqrt{3}+1)}=\frac{-2(\sqrt{3}+1) }{2(\sqrt{3}+1)}=\frac{-2 }{2}= \boxed{ -1}[/tex]