The scale factor is always the ratio of new image with respect to the old image.
6) The scale factor as per the image is 3:1 or 3.
7) The New image is P'Q'R'S' and old image is PQRS so the scale factor is given by:
Q'R':QR=3:6 or 1:2.
The scale factor is 1/2.
8) Here the pair of congruent angles is:
The proportional sides are:
So FG corresponds to RS, GH corresponds to TS, HF corresponds to TR.