A factory makes choclates. A box of Chocolate contains 0,9 kg. The purchase price of the ingredients is $ 10.00 per kg. While making the Chocolates in the factory there is a waste of 20% of the gross usage of ingredients. The waste can be sold for 50% of the purchase price of the ingredients.

Question: calculate the costs of the ingredients per box of chocolates

I would like to know how this is calculated step by step.

Thank you in advance.