Dinamic pricing with quantity

Hello! I am currently an intern making a online printing website, and i reached a roadblock. The user will send a pdf file and the website counts the amount of pages it has. However, how can i make the pricing vary with quantity? I have used this plugin: Advanced Product Fields for WooCommerce, but it doesnt allow quantity (the quantity are the amount of pages the pdf has) changing fees. Either in the color of the print, format, type of paper, etc. Some help would be very appreciated. Thank you