Answer:
1. It would be the second block. Bill reads 3 books EACH week. I know you’re looking for that X to be 1 but if you look 3 books x 5 weeks = 15 books and so on.
2. It would be the first block. Exactly on 6 weeks he reads 6 books meaning that by week 3 (which is half) he would have read haof the books (2). And same for week 12 you and another 4 which gets you 8 books.
3. It’s the last block. On week 12 he read 4 books. Half of 12 is 6 so it would be half books and week 3 is half of that which is 1 book per 3 weeks.
4. Is the third block. (Process of elimination lol) but also easily you can find the rate of each week by dividing the 15 books by 10 weeks which gets you 1.5 books read per week