You may have incorrectly simplified this to $\displaystyle{\left|{b}+{4}\right|}={9}\usepackage{cmbright}\Huge\$ , and then solved $\displaystyle{b}+{4}=-{9}\usepackage{cmbright}\Huge\$ or $\displaystyle{b}+{4}={9}\usepackage{cmbright}\Huge\$ . Actually it simplifies to $\displaystyle{\left|{b}+{4}\right|}=-{11}\usepackage{cmbright}\Huge\$ .