1,200 exercise books with a cost of 0.25 yuan are sold at a price of 40% of the profit. When 80% of the exercise books are sold, the remaining exercise books are sold at a discount, and the profit obtained is 86% of the predetermined profit. How much is the discount on the list price when the remaining exercise books are sold?
成本0.25元的练习本1200本，按40%的利润定价出售，当销掉80%后，剩下的练习本打折扣出售，结果获得的利润是预定的86%．问剩下的练习本出售时按定价打了多少折扣？
<result>8</result>