How does Google Books pay?

I'm curious about how Google Books handles payments for the authors and publishers whose works they digitize and distribute. Can you explain the payment process in detail? Specifically, I'd like to know how Google determines the amount to pay, whether it's based on sales, page views, or some other metric. Additionally, I'm interested in understanding how frequently payments are made and if there are any fees or deductions taken from the payments before they reach the authors and publishers. Can you provide a clear overview of the payment system used by Google Books?