Question

Решить задачу. Лена прочитала за 3дня книгу. В 1 день она прочитала 20%, от всей книги . Во 2 день 65 % остатка. А в 3 день 14 страниц. Сколько страниц в книге?

Answer 1

100%-20%=80% - столько осталось прочитать после первого дня
80/100*65=26 (стр) - столько она прочитала во второй день
26+14=40 (стр) - столько она прочитала за второй и третий день
40 стр - 80% всей книги
40/80*100=50
Ответ: всего в книге 50 страниц

Answer 2

Problem Analysis

Lena read a book over the course of 3 days. On the first day, she read 20% of the entire book. On the second day, she read 65% of the remaining pages. And on the third day, she read 14 pages. We need to determine the total number of pages in the book.

Solution

Let's solve this problem step by step.

1. On the first day, Lena read 20% of the entire book. 2. On the second day, she read 65% of the remaining pages. 3. On the third day, she read 14 pages.

To find the total number of pages in the book, we need to work backward from the information given.

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

1. On the first day, Lena read 20% of the entire book, which is 0.2x pages. 2. On the second day, she read 65% of the remaining pages. The remaining pages after the first day would be (1 - 0.2) * x = 0.8x. So, she read 0.65 * 0.8x pages on the second day, which is 0.52x pages. 3. On the third day, she read 14 pages.

Now, we can set up an equation to solve for x:

0.2x + 0.52x + 14 = x

Simplifying the equation:

0.2x + 0.52x + 14 - x = 0 0.72x + 14 = x 14 = x - 0.72x 14 = 0.28x x = 14 / 0.28 x = 50

Therefore, the total number of pages in the book is 50.

Answer

The total number of pages in the book is 50.