Slope = rise / run
The first point is at (-6, -1) and the second is at (6, -2).
When looking for the rise, compare the y values.
From the first to second y values, it goes down 1, or -1.
When looking for the run, compare the x values.
From the first to second x values, it goes 12 to the right.
so put the rise (-1) over run (12) and your answer and slope is -1/12.