The scale factor of the giiven dilation is 5.
In transformation concept in maths, scale factor is simply the factor by which an object was increased or reduced.
Now, from the brainly link attached it is seen that the two triangles, ABC and A'B'C are similar. Thus;
CA/CA' = BA/B'A'
Thus;
CA/CA' = 4/20
CA/CA' = 1/5
Thus BA/B'A' = 1/5
5BA = B'A'
Thus, the scale factor of the dilation is 5.
Read more about Scale Factor at; https://brainly.com/question/1486931