Answer:
Scale factor: 2.5
Explanation:
Scale factor is the ratio between corresponding measurements. And a pre image is basically an (original image) while an image is the translated version of the original.
I'm not sure what the best way to explain my answer is, but you can either multiply or divide to find the answer.
4 x 2.5 = 10
8 x 2.5 = 20
10 x 2.5 = 25
5 x 2.5 = 12.5
10/4 = 2.5
20/8 = 2.5
25/10 = 2.5
12.5/5 = 2.5