Marked price of Bajaj iron, Usha iron and Philips iron are Rs.2400, Rs.3000 and Rs.3600 respectively. Bajaj iron is sold at a discount of 5%, Usha iron at a discount of 8% and Philips iron at a discount of 10%, yet the shopkeeper got an overall profit of 20%. If cost price of Bajaj iron is half of Usha iron and the cost price of Usha iron is half of Philips iron, find the cost price of Usha iron. (approx.)