1. **State the problem:** We are given the equation of a line in slope-intercept form: $y = mx + c$. 2. **Identify the line from the graph:** The blue line passes through the origin $(0,0)$ and points like $(1,1)$ and $(2,2)$, indicating the slope $m$ is 1 and the y-intercept $c$ is 0. 3. **Formula and explanation:** The slope-intercept form of a line is given by: $$y = mx + c$$ where $m$ is the slope and $c$ is the y-intercept. 4. **Calculate slope $m$:** Using points $(0,0)$ and $(1,1)$, $$m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{1 - 0}{1 - 0} = 1$$ 5. **Determine y-intercept $c$:** Since the line passes through the origin, $$c = 0$$ 6. **Point P on the y-axis:** The orange point $P$ is at $(0,3)$, which means it lies on the y-axis where $x=0$ and $y=3$. 7. **Summary:** The blue line equation is: $$y = 1 \cdot x + 0 = x$$ The point $P$ is not on this line since its $y$-value is 3, not 0. **Final answer:** The equation of the blue line is $$y = x$$