Help for calcul

I need help: I ??have a product 1 with a price of € 10 per M2 and a product 2 with a price of € 20 per M2. People should choose the width and height of the product. I would like to have a price per M2 depending on the height and width chosen and depending on the price of product 1 or 2

Second question … I want to add this total price to a fixed price of another product 3 to 15 € and product 4 to 25 € if people add product 3 or 4 (which is not an obligation)

Thank you very much