# How do I find the slope of the line which passes through the points (-10, -9) and (-10, 8)?

slope $= m = \frac{{y}_{2} - {y}_{1}}{{x}_{2} - {x}_{1}} = \frac{8 - - 9}{- 10 - - 10} = \frac{17}{0} = \text{undefined}$