\(\bf {{ a}}\%\ of\ b \implies \cfrac{{{ a}}}{100}\cdot b\implies {{ a}}\div 100\cdot b\qquad thus\\\\
-----------------------------\\\\
{{ 66\frac{2}{3}}}\%\ of\ 39 \implies \cfrac{{{ 66\frac{2}{3}}}}{100}\cdot 39\implies {{ 66\frac{2}{3}}}\div 100\cdot 39\)
and surely you know how to change the mixed fraction to "improper fraction", or just use a decimal value, that'd work too
