1. **State the problem:** We need to find the slope of the line representing Riley's distance over time during the first 5 minutes of the race and write an equation for distance $y$ in terms of time $x$. 2. **Identify points from the graph:** The line passes through points $(0,3)$ and $(4,0)$ where $x$ is time in minutes and $y$ is distance in kilometers. 3. **Calculate the slope:** The slope formula is $$m = \frac{\text{change in } y}{\text{change in } x} = \frac{y_2 - y_1}{x_2 - x_1}$$ Substitute the points: $$m = \frac{0 - 3}{4 - 0} = \frac{-3}{4} = -\frac{3}{4}$$ 4. **Write the equation of the line:** Using point-slope form $y = mx + b$, where $b$ is the y-intercept (distance at time 0), which is 3: $$y = -\frac{3}{4}x + 3$$ 5. **Check the equation:** At $x=4$ minutes, substitute into the equation: $$y = -\frac{3}{4} \times 4 + 3 = -3 + 3 = 0$$ This matches the graph point $(4,0)$, confirming the equation is correct. **Final answer:** The slope is $-\frac{3}{4}$ and the equation is $$y = -\frac{3}{4}x + 3$$