Answer
$\frac{-1}{3x+5}$ (and $x\ne\frac{5}{3}$).
Work Step by Step
The product of a binomial sum and a binomial difference is: $(A+B)(A-B)=A^2-B^2$.
Hence here: $\frac{3x-5}{25-9x^2}=\frac{3x-5}{-((3x)^2-5^2)}=\frac{3x-5}{-(3x+5)(3x-5)}=\frac{-1}{3x+5}$ (and $x\ne\frac{5}{3}$).
