Answer
$x^{2y}$
Work Step by Step
We are given the expression $x^{9y}\times x^{-7y}$.
We can use the product rule to simplify, which holds that $a^{m}\times a^{n}=a^{m+n}$ (where a is a real number, and m and n are positive integers).
$x^{9y}\times x^{-7y}=x^{9y+(-7y})=x^{2y}$