An equation in the form $\displaystyle{x}={a}\usepackage{cmbright}\Huge\$ describes a vertical line, so a line parallel to $\displaystyle{x}={3}\usepackage{cmbright}\Huge\$ will be in the form $\displaystyle{x}=\usepackage{cmbright}\Huge\$ constant (other than 3). The line $\displaystyle{x}={8}\usepackage{cmbright}\Huge\$ fits this description.