Question

реши задачу. вычисли и запиши ответ. книга дороже тетради на 80 руб. за книгу и тетрадь заплатили 120 руб. сколько нужно заплатить за 5 таких тетрадей и 3 такие книги?

Answer 1

Problem Analysis

We are given that a book is more expensive than a notebook by 80 rubles. The total cost of a book and a notebook is 120 rubles. We need to find the cost of 5 notebooks and 3 books.

Solution

Let's assume the cost of a notebook is x rubles. Since the book is more expensive than the notebook by 80 rubles, the cost of the book would be x + 80 rubles.

According to the given information, the total cost of a book and a notebook is 120 rubles. So we can write the equation:

x + (x + 80) = 120

Simplifying the equation, we get:

2x + 80 = 120

Subtracting 80 from both sides, we have:

2x = 40

Dividing both sides by 2, we get:

x = 20

Therefore, the cost of a notebook is 20 rubles.

To find the cost of 5 notebooks, we multiply the cost of one notebook by 5:

5 * 20 = 100 rubles

To find the cost of 3 books, we multiply the cost of one book by 3:

3 * (20 + 80) = 3 * 100 = 300 rubles

So, the cost of 5 notebooks and 3 books would be 100 rubles and 300 rubles, respectively.

Answer

The cost of 5 notebooks would be 100 rubles and the cost of 3 books would be 300 rubles.