1. **State the problem:** Find the slope of the line passing through the points $(-40, 78)$ and $(18, 40)$. 2. **Formula for slope:** The slope $m$ between two points $(x_1, y_1)$ and $(x_2, y_2)$ is given by $$m = \frac{y_2 - y_1}{x_2 - x_1}$$ This formula calculates the "rise" over the "run" or the change in $y$ divided by the change in $x$. 3. **Substitute the points:** Using $x_1 = -40$, $y_1 = 78$, $x_2 = 18$, and $y_2 = 40$, we get $$m = \frac{40 - 78}{18 - (-40)} = \frac{40 - 78}{18 + 40}$$ 4. **Simplify numerator and denominator:** $$m = \frac{-38}{58}$$ 5. **Simplify the fraction:** Both numerator and denominator are divisible by 2, so $$m = \frac{\cancel{2} \times (-19)}{\cancel{2} \times 29} = \frac{-19}{29}$$ 6. **Final answer:** The slope of the line is $$m = -\frac{19}{29}$$ This means the line falls $19$ units vertically for every $29$ units it moves horizontally to the right.