First add 10 to both sides of the equation, then rewrite $\displaystyle{\left|{3}{y}+{7}\right|}={13}\usepackage{cmbright}\Huge\$ as:

$\displaystyle{3}{y}+{7}={13}\usepackage{cmbright}\Huge\$ or $\displaystyle{3}{y}+{7}=-{13}\usepackage{cmbright}\Huge\$

Subtract 7 from both sides of both equations: $\displaystyle{3}{y}={6}\usepackage{cmbright}\Huge\$ or $\displaystyle{3}{y}=-{20}\usepackage{cmbright}\Huge\$

Divide both sides of both equations by 3: $\displaystyle{y}={2}\usepackage{cmbright}\Huge\$ or $\displaystyle{y}=-\frac{{20}}{{3}}\usepackage{cmbright}\Huge\$