Answer:
The slope of the line passing through the points (1, -1) and (4, 8) is 3.
Explanation:
The slope of a line passing through two points (x1, y1) and (x2, y2) is given by the following formula:

Here, the given points are (1, -1) and (4, 8). So,

Therefore, the slope of the line passing through the points (1, -1) and (4, 8) is 3.