The slope of a line passing through two points $(x_1, y_1)$ and $(x_2, y_2)$ is calculated using the formula:

$m = \frac{y_2 - y_1}{x_2 - x_1}$

Substituting the points $(4, -1)$ and $(2, 3)$ into the formula:

$m = \frac{3 - (-1)}{2 - 4} = \frac{3 + 1}{2 - 4} = \frac{4}{-2} = -2$

So, the slope of the line is $m = -2$.

Would you like more details or have any further questions?

Here are 5 related questions to explore this topic:

1. How do you find the equation of a line given two points?
2. What is the slope of a vertical line?
3. What does the slope represent in the context of a graph?
4. Can the slope of a line be zero? If so, under what conditions?
5. How do you graph a line if you know the slope and a point?

Tip: The slope tells you how steep a line is and whether it rises or falls as you move from left to right on a graph.