Triangle ABCis transformed with the center of dilation at the origin. Pre-image: A ABC with vertices A(2, 5), B(6, 10), C(9, -1) Image: A A'B'C' with vertices A' (0.5, 1.25), B'(1.5, 2.5), C'(2.25, -0.25) What is the scale factor of the dilation that maps the pre-image to the image? Enter your answer in the box.