Answer: The scale factor was used in the dilation = -4
Explanation:
- The scale factor of dilation is the ratio of the side-length in the image to the corresponding side length in the pre-image.
From the given picture, the length of side SR in pre-image = 3cm
The length of corresponding side S'R' in image = 12 cm
Then , the scale factor of dilation will be :-

Since , the enlargement appearing on the other side , then the scale factor becomes negative.
Hence, the scale factor of this dilation =-4.