Abambam

I want help correlating two sets of data. Let's assume a publisher prints 100000 copies of a book. The size of that book is 1131 square mm and the cost of placing an advert on the back cover of that book is $3415.15. If another publisher decides to print 5000 copies of the same book, number of pages being same but the size reduces to 211.05 square mm, what would be the advert rate on the back cover? i,ll appreciate the mathematical basis for any solution. Regards