What is the scale Factor?

Answer:
k = [tex]\frac{3}{5}[/tex]
Step-by-step explanation:
The scale factor k is the ratio of corresponding sides, image to original, that is
k = [tex]\frac{B'C'}{BC}[/tex] = [tex]\frac{12}{20}[/tex] = [tex]\frac{3}{5}[/tex]