so the students are on 5:6 ratio from volleyball to football, and we know there are 220 students in total.
[tex]\bf \cfrac{volleyball}{football}\qquad 5:6\qquad \cfrac{5}{6}\implies \cfrac{5\cdot \frac{220}{5+6}}{6\cdot \frac{220}{5+6}}\implies \cfrac{5\cdot 20}{6\cdot 20}\implies \cfrac{100}{\stackrel{football}{120}}[/tex]