Multiply both sides of the equation by 6:

$\displaystyle{6}\cdot\frac{{x}}{{6}}={6}\cdot{7}\usepackage{cmbright}\Huge\$ or $\displaystyle\frac{{6}}{{6}}\cdot{x}={42}\usepackage{cmbright}\Huge\$ or $\displaystyle{x}={42}\usepackage{cmbright}\Huge\$