13. a) A retailer allowed 4% discount on his goods to make 20% profit and sold a refrigerator for Rs 10,848 with 13% VAT. (i) Find the selling price of refrigerator without VAT. (ii) How much is the marked price of the refrigerator? (iii) Calculate the cost price of the refrigerator to the retailer. (iv) How much is the selling price of the refrigerator if the retailer wants to make only 15% profit? (v) By how much is the discount to be increased so that he can gain only 15%?