Answer
$(3x+5y)(3x-5y)$
Work Step by Step
If $a$ and $b$ are real numbers, we know that $a^{2}-b^{2}=(a+b)(a-b)$. In words, the difference of the squares of two terms factors as a product of a sum and a difference of those terms.
Therefore, we know that $9x^{2}-25y^{2}=(3x+5y)(3x-5y)$. In this case, $a=3x$ and $b=5y$.
