The answer is (-5x - 3) (-5x + 3).
The difference of squares formula: (a + b) (a - b) = a^2 — b^2 can be applied to your given problem. If you use the FOIL method to verify whether it’s the correct answer:
(-5x - 3) (-5x + 3) = 25x^2 - 15x + 15x - 9
= 25x^2 - 9.