1. The problem asks for the slope of a line perpendicular to the line given by the equation $y = 8x + 5$. 2. Recall that the slope-intercept form of a line is $y = mx + b$, where $m$ is the slope. 3. The slope of the given line is $m = 8$. 4. Important rule: The slope of a line perpendicular to another line is the negative reciprocal of the original slope. 5. The negative reciprocal of $8$ is $$-\frac{1}{8}$$. 6. Therefore, the slope of the line perpendicular to $y = 8x + 5$ is $$-\frac{1}{8}$$.