Question

На прошлой неделе Саша прочитал 3/7 всей книги, а на этой неделе - половину оставшихся страниц да ещё 20 страниц и дочитал книгу до конца. Сколько страниц в книге?

Answer 1

В книге x страниц. На прошлой неделе прочитал $\frac37x$ страниц, осталось $x-\frac37x=\frac47x$ страниц.
На этой неделе прочитал $\frac12\cdot\frac47x=\frac27x$ страниц, осталось $\frac27x$ или 20 страниц.
$\frac27x=20\\x=20:\frac27\\x=20\cdot\frac72\\x=10\cdot7\\x=70$
В книге 70 страниц.

Answer 2

Calculation of the Number of Pages in the Book

To determine the number of pages in the book, we need to analyze the information provided. According to the given information, Sasha read 3/7 of the entire book last week and half of the remaining pages this week, along with an additional 20 pages.

Let's break down the calculation step by step:

1. Last week, Sasha read 3/7 of the book. 2. This week, Sasha read half of the remaining pages along with an additional 20 pages. 3. By adding the pages read last week and this week, we can calculate the total number of pages read. 4. Subtracting the total number of pages read from the total number of pages in the book will give us the number of remaining pages. 5. Finally, we can calculate the total number of pages in the book by adding the number of pages read and the number of remaining pages.

Let's perform the calculation:

1. Last week, Sasha read 3/7 of the book. 2. This week, Sasha read half of the remaining pages along with an additional 20 pages.

Let's assume the total number of pages in the book is x.

Last week, Sasha read 3/7 of the book, which is equal to (3/7)x pages.

This week, Sasha read half of the remaining pages along with an additional 20 pages. The remaining pages can be calculated as (1 - 3/7)x pages. Therefore, Sasha read (1 - 3/7)x/2 + 20 pages this week.

Adding the pages read last week and this week, we get:

(3/7)x + (1 - 3/7)x/2 + 20

Simplifying the expression:

(3/7)x + (4/7)x/2 + 20

Combining the fractions:

(6/14)x + (4/14)x + 20

Simplifying further:

(10/14)x + 20

Now, we can calculate the number of remaining pages by subtracting the total number of pages read from the total number of pages in the book:

Total number of remaining pages = Total number of pages in the book - Total number of pages read

Total number of remaining pages = x - [(10/14)x + 20]

Simplifying the expression:

Total number of remaining pages = (14/14)x - (10/14)x - 20

Total number of remaining pages = (4/14)x - 20

Finally, we can calculate the total number of pages in the book by adding the number of pages read and the number of remaining pages:

Total number of pages in the book = Total number of pages read + Total number of remaining pages

Total number of pages in the book = [(3/7)x + (1 - 3/7)x/2 + 20] + [(4/14)x - 20]

Simplifying the expression:

Total number of pages in the book = (3/7)x + (1 - 3/7)x/2 + 20 + (4/14)x - 20

Total number of pages in the book = (3/7)x + (1 - 3/7)x/2 + (4/14)x

Now, we can solve this equation to find the value of x, which represents the total number of pages in the book.

Please note that the given search results do not provide any relevant information to directly answer this question. Therefore, we need to rely on the provided information and perform the calculation as explained above.