Product unit and packaging price

Hello,

I explain my problem. (this is an example)

I have products that the package is 12 pieces and the weight of a single product is 100gr. price per unit is 1 €.

How can I add the new product as a unit price, unit weight and specify that this product packaging is 12 pieces.

I would like that when I sell this product (Unit) it automatically counts me the packaging (12 pcs) with total price and total weight and inside the invoice you can see unit price, packaging unit amount and total price.

Thank you