You must completely simplify inside parentheses before you do other operations. The numerator is $\displaystyle{{\left({2}+{{2}}^{{3}}\right)}}^{{2}}={{\left({2}+{8}\right)}}^{{2}}\usepackage{cmbright}\Huge\$ . At this point you may have squared the 8 and then added the 2, which would be correct for $\displaystyle{2}+{{8}}^{{2}}\usepackage{cmbright}\Huge\$ . The correct value of the numerator is $\displaystyle{{\left({10}\right)}}^{{2}}={100}\usepackage{cmbright}\Huge\$ . The correct answer is 20.