Answer:
-1/8
Explanation:
Perpendicular slopes are negative reciprocals
The slope of y=8x+5 is 8, because it is in slope intercept form: y=mx+b form, where m is the slope.
Negative:
8/1--> -8/1
Reciprocal:
Flip the numerator and denominator
-8/1--> -1/8
So, the perpendicular slope of 8 is -1/8