Answer: 293 books were bought last year.
Step-by-step explanation
The number of books purchased this year is 15% more than that of last year. If the number of books bought this year is 345 books. Then last year the number of books bought is 345 x 15% = 51.75 appx 52 books
The number of books bought last year will be 345 - 52 = 293 books