There are 5,040 different ways in which she can order the books.
We know that Donna has 9 books, but 2 of these books already have fixed positions (the first one and the last one).
So we only need to order the remaining 7 books in 7 positions.
And so on for the remaining positions.
The total number of different combinations in which she can order the books is given by the product between the numbers of options above, so we will get:
C = 7*6*5*4*3*2*1 = 5,040
If you want to learn more about combinations:
https://brainly.com/question/251701
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