[tex]\stackrel{mixed}{6\frac{3}{7}}\implies \cfrac{6\cdot 7+3}{7}\implies \stackrel{improper}{\cfrac{45}{7}} \\\\[-0.35em] ~\dotfill\\\\ \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{\frac{45}{7}\textit{\% of 4570}}{\left( \cfrac{~~\frac{45}{7}~~}{100} \right)4570}\implies \left( \cfrac{45}{700} \right)4570~~ \approx~~293.79[/tex]