I'm having a brain freeze and am going round in circles trying to figure this one out. Hopefully someone can help me out in terms of what I need to include and how to set it out on Excel.

EG:
I have a 72 page catalogue of products. Each page has anything from 1 to 40 products on it.
I pay £31,000 for 50,000 catalaogues which generates £1m sales in the year

Page 1 shows 20 products (Toy1-Toy20), and generates £11,720 for the year
Toy1 takes up 0.035 of the page space and generates £1,793 for the year.
Toy2 takes up 0.045 of the page space and generates £750 for the year.

I'm trying to figure out what each product contributes in terms of the overall catalogue but Im struggling to get started on this one? Any suggestions/ideas greatly appreciated (not sure if this is an Excel query or a maths query)?