Parallel lines have the same slope, so if we find the slope of the line shown, the slope of the line parallel to it will be the same.
To find the slope, we find the rise divided by the run, or the change in x values divided by the change in y values.
slope = m = (y1 - y2)/(x1 - x2) = (3-2)/(0-3) = 1/(-3) = -1/3
Therefore, the slope is -1/3, and so the slope of the parallel line is also -1/3.
Your answer is -1/3.
Hope this helps!