Though you correctly substituted the slope $\displaystyle-\frac{{3}}{{2}}\usepackage{cmbright}\Huge\$ into $\displaystyle{y}={m}{x}+{b}\usepackage{cmbright}\Huge\$ , you then substituted the y-value, $\displaystyle-{2}\usepackage{cmbright}\Huge\$ , from the ordered pair for b. Instead, you should substitute the coordinates of the point $\displaystyle{\left(-{4},-{2}\right)}\usepackage{cmbright}\Huge\$ for x and y in $\displaystyle{y}=-\frac{{3}}{{2}}{x}+{b}\usepackage{cmbright}\Huge\$ and solve for b.