A dilation is a non rigid transformation. We know that a center of a transformation expect translations mean that it dont matter what change we do to the the pre image to get the new image. The center will stay where it was at all times. Looking at the figure, between the pre image and new image the only point that stays is Point K and point K' . so K is the center of the dilation and that at (-8,3).. Since the pre image is smaller than the new image we know the image scale factor is greater than 1 so the scale factor is expanding. To find the scale let look point K and L we need to find how far are they away from each other and which in this case is 4. Now let look at point K' and Point L'. There distances is 10. You can do the same for K and J. K and J distance is 2 units right and 4 units down. K' and J' distance is 5 units right and 10 units down.
Using this let set a proportion of one point from bigger figure to smaller figure. Distance in current image/ Distance in pre image. Let use K and J so it will be 10/4=2.5 so the scale factor is 2.5
Alex is making a square with 4 corners, brittanie is making a triangle with 3 corners. That's the difference, hope it helped a little, it's not a full answer but maybe it will help.
