the percent of x out of n is given by
[tex]\frac{x}{n}\times100\text{ \%}[/tex]
In this case,
[tex]x=20,n=75[/tex]
Therefore,
[tex]\frac{20}{75}\times100\text{ \%}=\frac{4}{15}\times100\text{ \%}=\frac{400}{15}\text{ \%}=\frac{80}{3}\text{ }\approx27\text{ \%}[/tex]
Hence, the percent of the teachers at the school teach math 27 %
