By selling an item, the producer, the wholesaler and the retailer all make profits at 20%. If the itewm sells for Tk.21.60 by the retailer, find the production cost of the item.

প্রশ্নঃ By selling an item, the producer, the wholesaler and the retailer all make profits at 20%. If the itewm sells for Tk.21.60 by the retailer, find the production cost of the item.