20. In the drama club, the number of boys is $80 \%$ of the number of girls. What percent of the number of boys does the number of girls represent in this drama club?
20. Let the number of girls be $a$, then the number of boys is $0.8 a$. The number of girls constitutes $\frac{a}{0.8 a} \cdot 100 \% = 125 \%$ of the number of boys.