The equation of the line is .
Let the slope of the line be .
Compare the equation of the line with the slope-intercept form .
Where m = slope of the line and b = y-intercept.
\Therefore .
Let the slope of another line be .
If the two nonvertical lines are parallel, then their slopes are equal. That is .
Therefore slope of the line parallel to the line is also 8.
If the two nonvertical lines are perpendicular, then their slopes are negative reciprocals of each other. That is .
Therefore slope of the line perpendicular to the line is
.
The slope of a parallel line is 8 and the slope of a perpendicular line is .