This equation works when $\displaystyle{y}={4}\usepackage{cmbright}\Huge\$ and $\displaystyle{x}={2}\usepackage{cmbright}\Huge\$ , but not for $\displaystyle{y}={9}\usepackage{cmbright}\Huge\$ and $\displaystyle{x}={3}\usepackage{cmbright}\Huge\$ .