The cost price of books mainly includes: printing fee, which varies according to the paper used and the printing process. Usually a printed sheet is about 0.6 to 1 yuan. Price 15 yuan's books, generally printed around 6 or 7 copies, at least close to 4 yuan.

Royalties are generally between 8%- 10%, and the lowest is 1.2 yuan.

Others include typesetting, editing, logistics and other expenses.

According to this calculation, the cost price of this book should be at least 5 yuan.

I hope you understand these and hope to adopt them.