Explain the relationship between multiplying and dividing by 10, 100, and 1,000 and moving the decimal point to the right or to the left.

You move to the left since you are multiplying

A) the scale factor is 1/4.
B) P'' = (-1, 0); Q'' = (0, -1); R'' = (2, -1).
C) No, they are not congruent.

The length of RQ is 8; after the dilation, the length of R'Q' is 2.  This means a scale factor of 2/8 = 1/4 was applied.

Reflecting this across the y-axis will negate the x-coordinate and leave the y-coordinate the same for each point.

The original triangle and the reflection are not congruent because the side lengths are not equal.