Lili is reading a 90-page fairy tale book. How many pages are there left? I read eight pages a day, and he has been reading for nine days.

Little Red read a fairy tale book for 15 pages a day. After four days, she still had 3/5 of the book left. Assuming that this fairy tale book has a total of x pages: Little Red read a total of 4x15 = 60 pages in four days. The remaining pages are 3/5 of the book, so there are: 60 pages/(3/5) = 120 pages. Therefore, this fairy tale book had a total of 120 pages.

Ya-chan reads a 114-page book, on average, 12 pages a day. After a few days, there are still 18 pages left. You can calculate it by the following steps: 114 pages/12 pages/day = 9 days Since Ya-chan needed 9 days to finish reading the book, he needed to read it from the 1st day to the 9th day, a total of 9 days. In these nine days, Ya-chan needed to read 12 pages a day, so in total, he would read: 12 pages/day x 9 days = 108 pages However, there were still 18 pages left, so Ya-chan had to read the remaining 18 pages every day: 18 pages/day = 1 page In other words, Ya-chan needed to read an extra page of the remaining 18 pages every day to finish the book.

Xiaofang had been reading for 5 days and there were 36 pages left, so she had read a total of $5/36 = 180$pages. Xiaofang still needed to read $86 - 180 =-104$pages every day. Because the number of pages was negative, Xiaofang read an average of $${-104}$pages per day.

Let's say the book has $x$pages. The original plan was to read $12$pages a day, so it would take $x$Mum $12$days to read the entire book. In fact, it would take an extra $8$a day to read the entire book, so it would take $x$Mum $12$ + $2$days. Because Xiao Ming finished the book two days earlier, he actually spent $x$Mum $12$ + $2$ - $1$days to finish the book. We can solve this problem by using the exponential sequence sum formula: $$x \div 12 + 2 - 1 = \frac{x \times (12+2)}{12}$$ The solution is $x=300$. Therefore, the book had a total of $300$pages.

If a book has 200 pages and you've read 40% of it, then the remaining pages are: 200 pages × 04 = 80 pages Thus, there were still 80 pages left in the book.

If Xiaoxiao had already read two-fifths of a 150-page book, then she had already read 150 × 2/5 = 60 pages. The remaining pages were 150 - 60 = 90 pages. Hence, Xiao Xiao still had 90 pages to read.

Xiao Ming had already read two-fifths of a 30-page book, so there were 30 - 2/5 = 30 - 04 = 296 pages left. Therefore, there were 296 pages left in the book.

Xiao Ming had already read two-fifths of a 150-page storybook, so he had already read 150 × 2/5 = 60 pages. Therefore, there were still 150 - 60 = 90 pages left in the storybook.