Monika is also responsible for the "spin kits" brand. They have been a very popular product among high school kids. Given the popularity, it has been difficult to keep them in stock. For this reason, they have priced the kit at $35. That has been a nice profit, since the cost of producing one (the value of the book) is only $16. Unfortunately, several competing products have emerged and the initial enthusiasm is also wearing off, so Monika is lowering the price to $20 a kit. How much impairment (if any) should Monika acknowledge?