ok so easy peasy
remember exponential laws
dividing
[tex] \frac{x^m}{x^n}=x^{m-n} [/tex]
also
(ab)/(cd)=(a/c)(b/d)
also
[tex]x^{-m}= \frac{1}{x^m} [/tex]
so
[tex] \frac{pq^7r^0}{pq^7r} =( \frac{p^1}{p^1} )( \frac{q^7}{q^7} )( \frac{r^0}{r^1} )[/tex]=(1)(1)[tex]( \frac{1}{r} )[/tex]=[tex] \frac{1}{r} [/tex]=[tex]r^{-1}[/tex]
answer is [tex]r^{-1}[/tex]
