Question

What is the slope of this line?

Answer 1

Since this line is descending, its slope should be negative:
Moreover the slope is nothing than the tangent of the angle formed with x-axis.
& the tangent of Ф = adjacent side/ opposite side).
If read well the graph you see that tan Ф = (4 units)/( - 8 units) = -4/8 = -1/2
Hence the slope = tan = -1/2

Answer 2

The slope of this line is -2.

rise/run

rise = 4
run = -2

4
------- = -2
-2

Using the points (1,0) & (0,2)

2 - 0 2
----------- = ----- = -2
0 - 1 -1