Find the slope using the given points: $\displaystyle{m}=\frac{{-{1}-{\left(-{4}\right)}}}{{-{6}-{\left(-{8}\right)}}}=\frac{{3}}{{2}}\usepackage{cmbright}\Huge\$

Substitute either point for x and y into $\displaystyle{y}=\frac{{3}}{{2}}{x}+{b}\usepackage{cmbright}\Huge\$ or $\displaystyle-{1}=\frac{{3}}{{2}}{\left(-{6}\right)}+{b}\usepackage{cmbright}\Huge\$

Solve for b: $\displaystyle-{1}=-{9}+{b}\usepackage{cmbright}\Huge\$ , so $\displaystyle{8}={b}\usepackage{cmbright}\Huge\$

Substitute the values of m and b into $\displaystyle{y}={m}{x}+{b}\usepackage{cmbright}\Huge\$ .