Answer:
[tex]r^{6}[/tex]
Step-by-step explanation:
Using the rule of exponents
[tex]\frac{a^{m} }{a^{n} }[/tex] = [tex]a^{(m-n)}[/tex] , then
[tex]\frac{r^{9} }{r^{3} }[/tex] = [tex]r^{(9-3)}[/tex] = [tex]r^{6}[/tex]