To calculate the slope of a line given two points, you can use the slope formula:

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

where $(x_1, y_1)$ and $(x_2, y_2)$ are the coordinates of the two points.

Let's calculate the slope for each pair of points:

1. Points (3, 8) and (0, 4):

$m = \frac{{4 - 8}}{{0 - 3}} = \frac{{-4}}{{-3}} = \frac{4}{3}$

The slope is $\frac{4}{3}$.

2. Points (-1, 2) and (6, 5):

$m = \frac{{5 - 2}}{{6 - (-1)}} = \frac{{3}}{{6 + 1}} = \frac{3}{7}$

The slope is $\frac{3}{7}$.

3. Points (-4, -1) and (9, -3):

$m = \frac{{-3 - (-1)}}{{9 - (-4)}} = \frac{{-3 + 1}}{{9 + 4}} = \frac{{-2}}{{13}}$

The slope is $-\frac{2}{13}$.

Summary of Slopes:

1. Slope of line through (3, 8) and (0, 4): $\frac{4}{3}$
2. Slope of line through (-1, 2) and (6, 5): $\frac{3}{7}$
3. Slope of line through (-4, -1) and (9, -3): $-\frac{2}{13}$

Would you like further details on how these calculations were performed? Here are some related questions:

1. How do you interpret the slope of a line in different contexts?
2. What is the significance of a positive versus negative slope?
3. How do you calculate the slope of a vertical or horizontal line?
4. Can a line have an undefined slope? If so, when?
5. How does the slope relate to the angle of inclination of a line?

Tip: Always make sure to subtract the coordinates in the same order for both the numerator and denominator to avoid mistakes when calculating slopes!