$989.001 + 1.00982 \times 76.792 = ?$

Which one of the following is the smallest fraction?
$\frac{6}{11}, \frac{13}{17}, \frac{19}{27}, \frac{21}{23}, \frac{5}{7}$

The simplification of $\left[\frac{1}{2}+\frac{1}{2}\left\{\frac{3}{4}-\frac{1}{2}\left(\frac{7}{8}-\frac{3}{4}\right)\right\}\right]$ yields

The value of $\frac{(81)^{3.6} \times (9)^{2.7}}{(81)^{4.2} \times 3}$ is

If $x = \sqrt{\frac{2+\sqrt{3}}{2-\sqrt{3}}}$,then what is the value of $(x^{2} - x - 9)$?

$(2 + \frac{3}{x}) \times (y + \frac{1}{2}) = \frac{31}{4}$,find the values of $x$ and $y$ if $x$ and $y$ are positive integers.