(x + 3) is a factor in x^2 - mx - 15

(x + 3) is a factor in x^2 - mx - 15. What is the value of m?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #17099