1. **State the problem:** Find the value of $r$ such that the line passing through the points $(-5, 2)$ and $(3, r)$ has a slope of $0$. 2. **Recall the slope formula:** The slope $m$ between two points $(x_1, y_1)$ and $(x_2, y_2)$ is given by $$m = \frac{y_2 - y_1}{x_2 - x_1}$$ 3. **Apply the formula:** Substitute the points and slope value: $$0 = \frac{r - 2}{3 - (-5)} = \frac{r - 2}{8}$$ 4. **Solve for $r$:** Multiply both sides by $8$ to clear the denominator: $$0 \times 8 = r - 2$$ $$0 = r - 2$$ Add $2$ to both sides: $$r = 2$$ 5. **Interpretation:** The value of $r$ must be $2$ for the slope of the line through the points to be zero, meaning the line is horizontal. **Final answer:** $$\boxed{2}$$