11.
[tex]a) \ \ \frac{8\sqrt{3}}{2\sqrt{3}} = 4\\\\b) \ \ 8\sqrt{7}+3\sqrt{7} = 11\sqrt{7}\\\\c) \ \ \frac{6+3\sqrt[3]{2}}{3} =\frac{3(2+\sqrt[3]{2})}{3} =2+\sqrt[3]{2}\\\\d) \ \ 5\sqrt[3]{6}+\sqrt[3]{6}+4\sqrt[3]{-6} = 6\sqrt[3]{6}-4\sqrt[3]{6} = 2\sqrt[3]{6}[/tex]