Part A:
The scale factor is 1/4, because you obtain the coordinates of points P', Q', R' by dividing the coordinates of P, Q and R respectively by 4.
Part B:
Reflecting about the y axis causes a sign swap in the x coordinate. So, the new point will be
Part C:
The triangles are similar, but not congruent. When you transform PQR into P'Q'R', you get a scaled version of the original triangle. This means that the angles and the proportion between sizes will be the same, but the length are scaled by 1/4, and the area is consequentially scaled by 1/16.
Triangles P'Q'R' and P''Q''R'' are congruent, so they are both similar but not congruent to the original triangle.