Final answer:
The equation that can be used to find x, the number of books the library had last year, is x + 45 = 2,759. Therefore correct option is D
Step-by-step explanation:
To find the number of books the library had last year, we can set up an equation using the given information. Let x represent the number of books the library had last year.
We know that over the summer, the library acquired another 45 books, so the total number of books after the acquisition is x + 45.
And we are told that the total number of books after the acquisition is 2,759, so we can set up the equation x + 45 = 2,759.
Therefore, the equation that can be used to find x, the number of books the library had last year, is x + 45 = 2,759.