[tex]\hspace{34em}|\\ \begin{array}{|c|ll} \cline{1-1} \textit{a\% of b}\\ \cline{1-1} \\ \left( \cfrac{a}{100} \right)\cdot b \\\\ \cline{1-1} \end{array}~\hspace{5em}\stackrel{\textit{20\% of 56.43}}{\left( \cfrac{20}{100} \right)56.43}\implies 11.286~\hfill \stackrel{about}{\approx 11.29}[/tex]
