Answer: 50 percent
Explanation: Keystone is a term used in retailing and which is related to pricing inventory. It is a method of pricing in which a particular commodity is priced for resale at an amount which is double the wholesale price or cost of the product.
Keystone pricing is calculated by multiplying the cost of the item by 1 to find the keystone mark-up because the mark-up equals the cost. For example, if the cost of the chocolate chips you sell in your store is $2, multiply $2 by 1 to find the keystone markup of $2. The add the keystone markup to the original cost to find the selling price, to get the keystone price.