WILL MARK BRAINILIST!! Triangle PQR is transformed to triangle P'Q'R. Triangle PQR has vertices P (3, -6), Q (0, -9), and R (-3, 0). Triangle P'Q'R has vertices P'Q'R has vertices P' (1, -2), Q' (0, 3), and R' (-1, 0).
What is the scale factor of the dilation that transforms triangle PQR to triangle P'Q'R? Explain your answer.