This is the solution to $\displaystyle\frac{{2}}{{5}}=\frac{{40}}{{n}}\usepackage{cmbright}\Huge\$ . Each ratio should compare things in the same order, such as horn players to string players. The correct proportion would have been $\displaystyle\frac{{2}}{{5}}=\frac{{n}}{{40}}\usepackage{cmbright}\Huge\$ . The answer is 16 horn players.