Typically, a store will discount an item by a percent of the original price. In this problem, an item that originally costs $15 is being discounted by 10%. So 10% off refers to the rate of discount.To solve this problem, we need a procedure.rocedure: 1  The rate is usually given as a percent. 2  To find the discount, multiply the rate by the original price. 3  To find the sale price, subtract the discount from original price.