$\frac{\sqrt{?}}{200} = 0.02$

In the following questions,two equations numbered $I$ and $II$ are given. You have to solve both the equations and give the answer.
$I$: $\frac{5}{7} - \frac{5}{21} = \frac{\sqrt{x}}{42}$
$II$: $\frac{\sqrt{y}}{4} + \frac{\sqrt{y}}{16} = \frac{250}{\sqrt{y}}$

If $\frac{52}{x} = \sqrt{\frac{169}{289}}$,then the value of $x$ is

$\sqrt{\frac{4}{3}}-\sqrt{\frac{3}{4}}=?$

Find the square root of $211600$.

The value of $\sqrt{10+\sqrt{25+\sqrt{108+\sqrt{154+\sqrt{225}}}}}$ is