Final answer:
The cost of five skirts can be represented by the expression 5(x - 7).
Step-by-step explanation:
The cost of five skirts can be calculated as follows:
- The original cost of one skirt is x-5 dollars.
- If three or more skirts are purchased, there is an additional two dollar reduction on each skirt.
- Therefore, the cost of each skirt, if three or more skirts are purchased, is (x-5) - 2 dollars.
- Thus, the total cost of five skirts would be 5 * ((x-5) - 2) dollars.
Therefore, the correct representation of the cost of five skirts is 5 * ((x-5) - 2), which simplifies to 5(x-7). Hence, the answer is option b) 5(x - 7).