​$$\text{Evaluate: } \sqrt{20 + \sqrt{17 + \sqrt{55 + \sqrt{73 + \sqrt{64}}}}}$$​​

Correct option is A

Given:​

​$$\sqrt{20 + \sqrt{17 + \sqrt{55 + \sqrt{73 + \sqrt{64}}}}}$$

Solution:

​$$\sqrt{20 + \sqrt{17 + \sqrt{55 + \sqrt{73 + 8}}}} \\ \ \\ =\sqrt{20 + \sqrt{17 + \sqrt{55 + \sqrt{81}}}} \\ \ \\ =\sqrt{20 + \sqrt{17 + \sqrt{55 + 9}}} \\ \ \\ =\sqrt{20 + \sqrt{17 + \sqrt{64}}} \\ \ \\ =\sqrt{20 + \sqrt{17 + 8}}\\ \ \\ =\sqrt{20 + \sqrt{25}} \\ \ \\ =\sqrt{20 + 5} \\ \ \\ = \sqrt{25} =5$$​​