Answer
$y^{17}z^{15}$
Work Step by Step
Based on the product rule for exponents, we know that $a^{m}\times a^{n}=a^{m+n}$ (where $m$ and $n$ are positive integers and $a$ is a real number).
Therefore, $(y^{2}z^{2})(y^{15}z^{13})=y^{2+15}\times z^{2+13}=y^{17}z^{15}$.