35 books are either for adults or for children.
number for adults : number for children = 6 : 1
How many more books are for adults than for children?

This is a problem about sharing a total amount into a given ratio. **Step 1: Find the total number of parts.** The ratio of adult books to children books is 6 : 1. The total number of parts is 6 + 1 = 7 parts. **Step 2: Find out how many books each part represents.** There are 35 books in total, which are shared across these 7 parts. Value of one part = Total books ÷ Total parts = 35 ÷ 7 = 5 books. **Step 3: Calculate the number of books in each category.** Number of adult books = 6 parts × 5 books per part = 30 books. Number of children books = 1 part × 5 books per part = 5 books. **Step 4: Find the difference.** The question asks for how many *more* adult books there are than children books. Difference = Number of adult books - Number of children books Difference = 30 - 5 = 25. Alternatively, after step 2, you can find the difference in parts (6 - 1 = 5 parts) and multiply that by the value of one part (5 parts × 5 books/part = 25).