Notice that the line goes down by 3 units for each 3 units that it goes to the right:
The slope of a line is defined as the ratio between the change in the variable y divided by the change in the variable x:
[tex]m=\frac{\Delta y}{\Delta x}[/tex]
In this case, Δy=-3 and Δx=3. Then:
[tex]m=\frac{-3}{3}=-1[/tex]
Therefore, the slope of the line is equal to -1.
