A book dealer allows 16 per cent discount to a retailer and the retailer allows 10 per cent discount to a customer. These both discounts are given on the printed price of the book. If the customer pays Rs 270 for a book and the dealer makes a profit of 5 per cent what is the cost price of the book for the dealer?
A shopkeeper purchased 150 identical pieces of calculators at the rate of Rs. 250 each. He spent an amount of Rs .2500 on transport and packing. He fixed the labeled price of each calculator at Rs. 320. However, he decided to give a discount of 5% on the labeled price. What is the percentage profit earned by him?