[tex]\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{6\% of 31960}}{\left( \cfrac{6}{100} \right)31960}\implies 1917.6~\hfill \underset{cost~price}{\stackrel{31960-1917.6}{30042.4}}[/tex]