If Xiao Hong had already read 40 pages of a book, which was two-fifths of the book, then Xiao Hong had already read 20% or 0.2 times the book. How many pages are there in the book? You can divide the number of pages by the number of pages in the book: (100% - 02) / 100% = 90% Therefore, Little Red only had 10 pages left.
Xiaowen had read two-fifths of the book, which meant that Xiaowen had read 2/5 * 170 = 48 pages. Therefore, there were still 170 - 48 = 122 pages that he had not read.
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 a book with a total of 240 pages and had already read two-fifths of the entire book, so he had already read 240 × 2/5 = 96 pages. Therefore, there were still 240 - 96 = 144 pages left.
This book had: 39 + 2/5 = 39 + 06 = 406 pages. Because the number of pages in a book must be an entire number, the decimals needed to be rounded to the nearest whole number. Therefore, the book had a total of 40 pages.
Xiao Ming had already read two-fifths of a 200-page storybook, which was 10 pages more. 200 pages × 2/5 + 10 pages = 40 pages The remaining pages were: 200 - 40 pages = 160 pages Therefore, Little Ming still had 160 pages left.
Assuming that the book has x pages, then Little Light has read 2/5x pages. Because Little Light counted 80 pages, there were: 2/5x + 80 = x Solve the equation: x = 50 Therefore, the book had a total of 50 pages.
This book was left: Two-fifths of the book is 18 pages, 2/5 = 9 pages (with two decimals) Therefore, there were still nine pages left in the book.
Xiaowen had read two-fifths of the book, which meant that Xiaowen had read 170 pages divided by 2 = 85 pages. There were still 170 - 85 pages = 85 pages that he had not read.
Let's say the book has $x$pages. Reading 15 pages a day, it would take Xiaohong $x$days to finish reading this book. The remaining pages were three-fifths of the book, which was $025x$. According to the question, it would take Xiaohong four days to finish reading this book. Therefore, we can write the equation: $$ x + 025x = 025 \times (x+4) $$ Solve this equation: $$ x = 30 $$ So this book has 30 pages.
A book of 90 pages, three-fifths read, then there was still: 90 - 3/5 * 90 = 90 - 36 = 54 pages. Therefore, there were still 54 pages left.