Question

Лилит вычитала 4 из количества книг в шкафу и умножила результат на 5. Мари вычитала из количества книг 8 и умножила результат на 7. Лилит и Мари получили одинаковый номер. Найдите количество книг в шкафу.​

Answer 1

Problem Analysis

In this problem, we are given that Lilith subtracted 4 from the number of books in the shelf and multiplied the result by 5. Marie, on the other hand, subtracted 8 from the number of books and multiplied the result by 7. Both Lilith and Marie obtained the same number as a result. We need to find the number of books in the shelf.

Let's assume the number of books in the shelf is represented by the variable 'x'. We can set up the following equations based on the given information:

Equation 1: (x - 4) * 5 = (x - 8) * 7

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

Solution

To solve the equation (x - 4) * 5 = (x - 8) * 7, we can start by expanding both sides of the equation:

5x - 20 = 7x - 56

Next, we can simplify the equation by combining like terms:

5x - 7x = -56 + 20

-2x = -36

To isolate 'x', we can divide both sides of the equation by -2:

x = (-36) / (-2)

x = 18

Therefore, the number of books in the shelf is 18.

Conclusion

Based on the given information, we have determined that there are 18 books in the shelf.