Triangle ABC is transformed with the center of dilation at the origin.
Pre-image: △ABC with vertices A(−5, −4), B(−7, 3), C(3, −2)
Image: △A′B′C′ with vertices A′(−3.75, −3), B′(−5.25, 2.25), C′(2.25, −1.5)
What is the scale factor of the dilation that maps the pre-image to the image?
Enter your answer in the box. Your answer must be a fraction, reduced to lowest terms.