Question: Work out the equation of the straight line shown below.
Give your answer in the form $y = mx + c$
Graph: a straight blue line on a coordinate grid, crossing the y-axis at $(0, 4)$ and passing through $(1, -1)$; position_hint \in \{center\}.
1. **State the problem:** Find the equation of the straight line passing through points $(0,4)$ and $(1,-1)$ in the form $y = mx + c$.
2. **Formula used:** The equation of a line is $y = mx + c$, where $m$ is the slope and $c$ is the y-intercept.
3. **Calculate the slope $m$:**
$$m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{-1 - 4}{1 - 0} = \frac{-5}{1} = -5$$
4. **Identify the y-intercept $c$:** The line crosses the y-axis at $(0,4)$, so $c = 4$.
5. **Write the equation:** Substitute $m = -5$ and $c = 4$ into $y = mx + c$:
$$y = -5x + 4$$
**Final answer:**
$$y = -5x + 4$$