Answer :
The easy way is to multiply 1/8 by 3: 1x3=3, 8x3=24, 3/24. Tony has 24 books :)
The question is asking to calculate the book that Tony have in all if one eight of his book are 3 mystery books, base on the questions, and on my further calculation, I would say that the answer would be 24 books. I hope you are satisfied with my answer and feel free to ask for more if you have questionsÂ