The retail price of a product is Tk. If the producer, the wholesaler and the retailer each sells the product at 20% profit, then what is the production cost of the product?

Suppose, production cost = 100 tk 20% profit, selling price=100+20=120 tk wholesale cost  price = 144 tk               selling price= (120+120x 20/100)=144 tk retailer, cost price =144 selling price = (144+144 x20/100)=172.8 tk retailer price 172.8 tk= production cost 100 tk retailer price 21.60 tk= production cost 100 X 21.60/172.8 tk=12.50 tk