We are given several points are asked to identify what type of slope has the line that joins them. So, let us first review the type of slopes.
There are 4 types: positive, negative, zero and undefined. Now, let us illustrate one line for each type
Positive slope
Negative slope
zero slope
Undefined slope
Note that for the case of the undefined slope, it corresponds to a vertical line. The easiest way to identify a vertical line is by noting that any two points of a verticval line have the same x-coordinate.
Then, by a quick inspection, we can see that points (-7,8) and (-7,0) have the same x coordinate. Thus, they line that joins them is a vertical line, which means that it has ań undefined
