Answer:
The scale factor is equal to

Explanation:
we know that
the scale factor is equal to divide the length of the corresponding side of the parallelogram WXYZ by the length of the corresponding side of the parallelogram RSTV
Let
z-----> the scale factor
x-----> the length side of the parallelogram WXYZ
y------> the length side of the parallelogram RSTV
so

In this problem we have


substitute

-----> is correct because is a reduction