You solved $\displaystyle{3}{\left|{m}-{7}\right|}+{9}>{30}\usepackage{cmbright}\Huge\$ , instead of $\displaystyle{3}{\left|{m}-{7}\right|}+{9}<{30}\usepackage{cmbright}\Huge\$ . You should first simplify to $\displaystyle{\left|{m}-{7}\right|}<{7}\usepackage{cmbright}\Huge\$ , and then rewrite without absolute value as $\displaystyle-{7}<{m}-{7}<{7}\usepackage{cmbright}\Huge\$ .