A bookstore bought an old book with the original price of 12.5 yuan, which was priced at a 60% discount and then sold at a profit of 20%. What's the price of this book? (do it by arithmetic)

Purchase price = 12. 50。 6=7。 5 yuan.

Price = 7. 5 * (1+20%) = 9 yuan.

During New Year's Day, a store sold a batch of goods at a reduced price. If you sell it at a 10% discount, you can make a profit of 2 15 yuan; If you sell it at a 20% discount, you will lose 125 yuan. What is the cost of this shipment?

Original price = (2 15+ 125)/(0. 9-0。 8) = 3400 yuan.

Cost = 3400 * 0. 9-2 15 = 2845 yuan