Answer:
Option D. 50 pairs of men's shoes.
Explanation:
To solve this problem you must apply the proccedure shown below:
1. You have that the situation is given by the following expression:

Where
is the number of women's shoes and
the numbers of men's shoes.
2. Therefore, if he does not have females costumers in a particular week, you have:

3. Substitute this into the first expression and solve for
:
