Answer :
This is where you would use this exponent property:
[tex] \frac{a^x}{a^y} =a^{x-y}[/tex]
In this case it would be
[tex] \frac{r^m}{r^n} =r^{m-n}[/tex]
So A.
[tex] \frac{a^x}{a^y} =a^{x-y}[/tex]
In this case it would be
[tex] \frac{r^m}{r^n} =r^{m-n}[/tex]
So A.