Question

The average brain is about 2% of a persons total body weight which fraction is equivalent to 2%

Answer 1

$\bf \begin{array}{|c|ll} \cline{1-1} \textit{a\% of b}\\ \cline{1-1} \\ \left( \cfrac{a}{100} \right)\cdot b \\\\ \cline{1-1} \end{array}\qquad \stackrel{\textit{2\% of anything}}{\left( \cfrac{2}{100} \right)anything}\implies \left( \cfrac{1}{50} \right)anything\implies(0.02)anything$

in short, we can change any percent formatted number to a decimal or fraction formatted one by simply dividing it by 100.