Answer: [tex]\frac{-7}{8}[/tex]
Step-by-step explanation:
First, we will need to find the slope of line r.
[tex]\displaystyle \frac{y_{2} -y_{1} }{x_{2} -x_{1}} =\frac{9-1}{8-1}=\frac{8}{7}[/tex]
Next, we know that perpendicular slopes are negative reciprocals of one another. To find the slope of line s, we will find the negative reciprocal of line r's slope.
[tex]\displaystyle \frac{8}{7} \rightarrow \frac{-7}{8}[/tex]