You must completely simplify the numerator before dividing.

$\displaystyle\frac{{{{\left({2}+{{2}}^{{3}}\right)}}^{{2}}}}{{{5}}}=\frac{{{{\left({2}+{8}\right)}}^{{2}}}}{{{5}}}=\frac{{{{\left({10}\right)}}^{{2}}}}{{{5}}}\usepackage{cmbright}\Huge\$

At this point, you may have divided 10 by 5 before computing the exponent. Here is the correct computation:

$\displaystyle\frac{{{{\left({10}\right)}}^{{2}}}}{{{5}}}=\frac{{100}}{{5}}={20}\usepackage{cmbright}\Huge\$

The correct answer is 20.