Answer
$p^{6}q^{5}$
Work Step by Step
Based on the quotient rule for exponents, we know that $\frac{a^{m}}{{a}^{n}}=a^{m-n}, a\ne0$ (where $m$ and $n$ are positive integers and $a$ is a real number).
Therefore, $\frac{p^{7}q^{20}}{pq^{15}}=p^{7-1}\times q^{20-15}=p^{6}\times q^{5}=p^{6}q^{5}$.