Ratio always means dividing.
Girls : Boys
or we can write it as
[tex] \frac{Girls}{Boys} [/tex]
[tex] \frac{21}{18}=[/tex] [tex] \frac{7}{6} [/tex] when we divide numerator and denominator with 3
That means that [tex] \frac{Girls}{Boys}=[/tex] [tex] \frac{7}{6} [/tex]
or Girls : Boys = 7 : 6
