We have clearance items that have two discounts applied to its price.
We can use a $1 item to find the final discount.
If we apply a 45% mark down, we will obtain a price of:

The discounted price is $0.55.
To this price we apply a 50% off. This can be expressed as:

This is the final price.
We can calculate the percentage of the original price as:

Answer: 27.5%