Given:
Point A'(6,3) is a dilation of point A(18,9).
To find:
The scale factor.
Solution:
We know that, if a point P is dilated by factor k and origin is the center of dilation, then

Let the scale factor for the given problem be k. So,

On comparing A'(18k,9k) and A'(6,3), we get



Therefore, the scale factor is
.