[tex]\bf \cfrac{total}{ratio}\qquad \cfrac{740}{17+3}\implies \boxed{37}\impliedby \textit{this means then}
\\\\\\
\cfrac{students}{staff}\qquad 17:3\implies \cfrac{17}{3}\implies \cfrac{17\cdot \boxed{37}}{3\cdot \boxed{37}}\implies \cfrac{629}{111}[/tex]
