Evaluate : 20 + 12 + 3 729 \,\, - 4 5 - 3 \,- 81 = ?

Answer: Option C

$$\sqrt{20}+\sqrt{12}+\text{root}3\text{of}729-\frac{4}{\sqrt{5}-\sqrt{3}}-\sqrt{81}$$
$$=2\sqrt{5}+2\sqrt{3}+9-$$   $$\left(\frac{4}{\sqrt{5}-\sqrt{3}}\times \frac{\sqrt{5}+\sqrt{3}}{\sqrt{5}+\sqrt{3}}\right)$$     $$-9$$
$$\begin{array}{rl}& =2\sqrt{5}+2\sqrt{3}+9-\left(\frac{4\left(\sqrt{5}+\sqrt{3}\right)}{2}\right)-9\\ & =2\sqrt{5}+2\sqrt{3}+9-2\sqrt{5}-2\sqrt{3}-9\\ & =0\end{array}$$