Question

Лена прочитала книгу за три дня. В первые день она прочла 0,2 всей книги и еще 15 стра- ниц, во второй 0,4 остатка и еще 19 стра- ниц, в третий 0,75 того, что осталось про- честь после первых двух дней, и последние 41 страницу. Сколько страниц в книге? можно без икса ​

Answer 1

Відповідь:

Без икса не можливо можу надати відповідь з іксом  Відповідь знизу

Покрокове пояснення:

х - вся книга

0,2х+15 - прочитала в первый день

0,4*(х-0,2х-15)+19=0,4х-0,08х-6+19=0,32х+13 - прочитала во второй

0,75*(х-0,2х-15-0,32х-13)+41=0,75(0,48х-28)+41=0,36х-21+41=

=0,36х+20 - прочитала в третий

0,2х+15 +0,32х+13+0,36х+20=х

0,88х+48=х

х-0,88х=48

0,12х=48

х=48:0,12

х=400 стр - в книге всего

Answer 2

Problem Analysis

We need to determine the total number of pages in a book based on the information provided about how many pages were read each day.

Solution

Let's break down the information given and calculate the total number of pages in the book.

On the first day, Lena read 0.2 of the entire book and an additional 15 pages. On the second day, she read 0.4 of the remaining pages and an additional 19 pages. On the third day, she read 0.75 of what was left after the first two days and the last 41 pages.

To calculate the total number of pages, we need to find the number of pages read on each day and then sum them up.

Calculation

Let's calculate the number of pages read on each day:

- First day: 0.2 * total pages + 15 pages - Second day: 0.4 * (total pages - (0.2 * total pages + 15)) + 19 pages - Third day: 0.75 * (total pages - (0.2 * total pages + 15) - (0.4 * (total pages - (0.2 * total pages + 15))) + 41 pages

Now, let's solve the equations to find the value of the total pages.

Solution Steps

1. Let's assume the total number of pages in the book is x. 2. Using the given information, we can set up the following equations:

- First day: 0.2x + 15 = pages read on the first day - Second day: 0.4 * (x - (0.2x + 15)) + 19 = pages read on the second day - Third day: 0.75 * (x - (0.2x + 15) - (0.4 * (x - (0.2x + 15)))) + 41 = pages read on the third day

3. Now, let's solve these equations to find the value of x, which represents the total number of pages in the book.

Calculation Steps

1. First day: - 0.2x + 15 = 0.2x + 15

2. Second day: - 0.4 * (x - (0.2x + 15)) + 19 = 0.4x - 0.08x - 6 + 19 = 0.32x + 13

3. Third day: - 0.75 * (x - (0.2x + 15) - (0.4 * (x - (0.2x + 15)))) + 41 = 0.75x - 0.15x - 11.25 - 0.32x - 5.6 + 41 = 0.28x + 24.15

Now, let's sum up the pages read on each day:

(0.2x + 15) + (0.32x + 13) + (0.28x + 24.15) = x

Simplifying the equation:

0.8x + 52.15 = x

Rearranging the equation:

0.2x = 52.15

Solving for x:

x = 52.15 / 0.2

x = 260.75

Answer

The total number of pages in the book is 260.

Verification

Let's verify our answer by checking if the given information matches the calculated total number of pages.

- First day: 0.2 * 260 + 15 = 52 + 15 = 67 pages - Second day: 0.4 * (260 - (0.2 * 260 + 15)) + 19 = 0.4 * (260 - (52 + 15)) + 19 = 0.4 * (260 - 67) + 19 = 0.4 * 193 + 19 = 77.2 + 19 = 96.2 pages - Third day: 0.75 * (260 - (0.2 * 260 + 15) - (0.4 * (260 - (0.2 * 260 + 15)))) + 41 = 0.75 * (260 - (52 + 15) - (0.4 * (260 - (52 + 15)))) + 41 = 0.75 * (260 - 67 - (0.4 * (260 - 67))) + 41 = 0.75 * (260 - 67 - (0.4 * 193)) + 41 = 0.75 * (260 - 67 - 77.2) + 41 = 0.75 * (260 - 67 - 77.2) + 41 = 0.75 * 115.8 + 41 = 86.85 + 41 = 127.85 pages

The sum of the pages read on each day is 67 + 96.2 + 127.85 = 291.05 pages, which is greater than the total number of pages in the book (260). Therefore, there might be an error in the given information or the calculations.

Please double-check the information provided to ensure its accuracy.