Sam read then books over the summer four were nonfiction the rest were fiction what percentage were fiction

We can start by using the formula for finding the percentage:

percentage = (part/whole) x 100

In this case:

- The part we're interested in is the number of fiction books, which is the total number of books minus the number of nonfiction books.
- The whole is the total number of books.

If we call the total number of books "T", we can write:

- Nonfiction books = 4
- Fiction books = T - 4

So the whole is T:

- Whole = T

Now we can substitute these values into the formula:

percentage = (part/whole) x 100
percentage = ((T - 4)/T) x 100

Simplifying this expression, we get:

percentage = (1 - 4/T) x 100

So the percentage of fiction books is given by this expression. We don't know the actual value of T, so we can't determine the exact percentage, but we can make some general observations:

- If T is very small (e.g. T = 5), then the percentage of fiction books will be close to 80% (i.e. 1 - 4/5 = 0.2 or 20%, so 100% - 20% = 80%).
- If T is very large (e.g. T = 100), then the percentage of fiction books will be close to 96% (i.e. 1 - 4/100 = 0.96 or 96%, so 100% - 96% = 4%).

To find the percentage of books that were fiction, we need to divide the number of fiction books by the total number of books and then multiply by 100.

Let's use the given information: Sam read ten books over the summer and four of them were nonfiction.

To find the number of fiction books, we subtract the number of nonfiction books from the total number of books: 10 - 4 = 6.

Now, we can calculate the percentage of fiction books:
(6 / 10) * 100 = 60%

So, 60% of the books Sam read over the summer were fiction.