You may not understand that the absolute value of a number is its distance from 0 on a number line. Both 7 and $\displaystyle-{7}\usepackage{cmbright}\Huge\$ are 7 units from 0. So this has two solutions: $\displaystyle{x}=-{7}\usepackage{cmbright}\Huge\$ and $\displaystyle{x}={7}\usepackage{cmbright}\Huge\$ .