Question

Ученик прочитал 1/8 книги , а затем 2/7 оставшейся части . После этого он заметил , что прочитал на 18 страниц меньше , чем ему осталось прочитать. Сколько страниц в книге?

Answer 1

(Х*7/8)*(2/7) +Х/8 - прочитано.
Значит прочитано Х*3/8
Х*3/8=Х*5/8-18
18=Х*2/8
Х=18*4
Ответ: 72 страницы

Answer 2

Problem Analysis

The problem states that a student read 1/8 of a book and then read 2/7 of the remaining part. After that, the student noticed that they had read 18 pages less than what was left to read. We need to determine the total number of pages in the book.

Solution

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

The student read 1/8 of the book, which is (1/8) * x pages.

After reading that portion, the student read 2/7 of the remaining part. The remaining part of the book is (7/8) * x pages, and the student read (2/7) * (7/8) * x pages.

According to the problem, the student read 18 pages less than what was left to read. So, we can set up the equation:

(1/8) * x + (2/7) * (7/8) * x = (7/8) * x - 18

Now, let's solve this equation to find the value of x.

Calculation

(1/8) * x + (2/7) * (7/8) * x = (7/8) * x - 18

Simplifying the equation:

(1/8) * x + (1/4) * x = (7/8) * x - 18

Multiplying through by 8 to eliminate the fractions:

x + 2x = 7x - 144

Combining like terms:

3x = 6x - 144

Subtracting 6x from both sides:

3x - 6x = -144

-3x = -144

Dividing by -3:

x = 48

Answer

The total number of pages in the book is 48.

Explanation

According to the calculations, the total number of pages in the book is 48. This means that the student read 1/8 of the book, which is 6 pages. After that, the student read 2/7 of the remaining part, which is (2/7) * (7/8) * 48 = 12 pages. The total number of pages read by the student is 6 + 12 = 18 pages. The student noticed that they had read 18 pages less than what was left to read, which confirms the solution.