Question

4. (3 балла) На первой полке в 6 раз больше книг, чем на второй. Если с первой полки снять 10книг, а на вторую поставить 20, то книг на полках станет поровну. Сколько книг на второй полке первоначально? Заранее спасибо О-О!!! 15 мин осталось​

Answer 1

УСЛОВИЕ:

Было:

Первая полка - 6х книг

Вторая полка - х книг

Стало:

Первая полка - 6х-10 книг

Вторая полка - х+20 книг

РЕШЕНИЕ:

6х-10 = х+20 (по условию, на полках книг стало поровну)

6х-х = 20+10

5х = 30

х = 30/5

х = 6 (книг) - было на второй полке первоначально

ОТВЕТ: 6 книг

Answer 2

Problem Analysis

We are given that there are 6 times more books on the first shelf than on the second shelf. If we remove 10 books from the first shelf and add 20 books to the second shelf, the number of books on both shelves will be equal. We need to find the initial number of books on the second shelf.

Solution

Let's assume the initial number of books on the second shelf is x. According to the given information, the number of books on the first shelf is 6 times more than the number of books on the second shelf, so the number of books on the first shelf is 6x.

After removing 10 books from the first shelf, the number of books on the first shelf becomes 6x - 10. After adding 20 books to the second shelf, the number of books on the second shelf becomes x + 20.

According to the problem, the number of books on both shelves will be equal after these operations. Therefore, we can set up the following equation:

6x - 10 = x + 20

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

6x - x = 20 + 10 5x = 30 x = 6

Therefore, the initial number of books on the second shelf is 6.

Answer

The initial number of books on the second shelf is 6.