Answer: Each chapter make up 10% of the book. 
Explanation:
Hi to answer this question we have to analyze the information given: 
- Book: 100 pages 
 - Each chapter: 10 
 
So, to find the percentage we have to divide the amount of pages of the book (100) by the number of pages that each chapter has (10): 
100/10 =10 % 
Since 100 pages are the 100% of the book, 10 pages are 10% of the book. 
Each chapter make up 10% of the book.