For ebooks you choose 35% or 70%. The 70% rate applies to books priced within Amazon's range (roughly $2.99–$9.99 in the US) and subtracts a small delivery fee. For paperbacks you earn 60% of the list price minus the printing cost on Amazon's marketplaces.
Print cost
Printing cost depends on page count, trim size and ink. That's why trimming pages can raise your paperback royalty.
No income promises
Royalty rates aren't sales. Most of a book's results come from the book itself, the cover, the category and the marketing behind it.
KDP's rules change from time to time. Check KDP's own help pages for the current requirements before you publish.