During a clothing store’s Bargain Days, the regular price for T-shirts is discounted by $5. There is a state sales tax of 5%, and the $5 discount is applied before the sales tax is calculated.
Write a rule for the function p(r) that expresses the final price p of a T-shirt with the discount applied and sales tax added.
How much would you pay during Bargain Days for a shirt regularly priced at $15.50?
I don't really understand what to do here, so an explanation would be greatly appreciated! :)