A person bought two bicycles for Rs. 1600 and sold the first at 10% profit and the second at 20% profit. If he sold the first at 20% profit and the second at 10% profit, he would get Rs. 5 more. Find the difference in the cost price of the two bicycles. 1. Rs 500 2. Rs 210 3. Rs 100 4. Rs 50 5. None of these