The point $\displaystyle{\left({0},-{5}\right)}\usepackage{cmbright}\Huge\$ is the y-intercept of the line, so $\displaystyle{b}=-{5}\usepackage{cmbright}\Huge\$ . The slope, m, is $\displaystyle-{3}\usepackage{cmbright}\Huge\$ . Substituting these values into the equation $\displaystyle{y}={m}{x}+{b}\usepackage{cmbright}\Huge\$ , you find $\displaystyle{y}=-{3}{x}-{5}\usepackage{cmbright}\Huge\$ .