Since the ratio of boys to girls is 5:4 and there are 60 girls, let b be the number of boys and g be the number of girls. Then:
[tex]\begin{gathered} \frac{b}{g}=\frac{5}{4} \\ \Rightarrow\frac{b}{60}=\frac{5}{4} \\ \Rightarrow b=\frac{5}{4}\times60 \\ \Rightarrow B=75 \end{gathered}[/tex]Therefore, there are 75 boys in the choir.
