Answer:
r= -189
Step-by-step explanation:
[tex]-13= r/9 + 8\\\\-13=\frac{r}{9}+8\\\\Switch\:sides\\\frac{r}{9}+8=-13\\\\\mathrm{Subtract\:}8\mathrm{\:from\:both\:sides}\\\frac{r}{9}+8-8=-13-8\\\\Simplify\\\frac{r}{9}=-21\\\\\mathrm{Multiply\:both\:sides\:by\:}9\\\frac{9r}{9}=9\left(-21\right)\\\\Simplify\\r=-189[/tex]
