A shopkeeper bought article ‘A’ for Rs. ‘x’ and marked it 20% above its cost price and sold it for Rs. 1800. Marked price of article ‘B’ is Rs. 1300 more than that of article ‘A’ while selling price of article ‘B’ is Rs. 650 more than that of ‘A’. Find the cost price of article ‘A’ if article ‘B’ is sold at a discount of 20%.