Question

Решите задачу. Вычислите и запишите ответ. Книга дороже тетради на 80 руб. За книгу и тетрадь заплатили 120 руб. Сколько нужно заплатить за пять таких тетрадей и три такие книги?

Answer 1

Тетраь х, тогда книга х+80, а вместе они    
х+х+80=120 р. 
2х+80=120 р
2х=40р
х=20 р- стоит тетрадь,
а книгастоит  х+80=20+80=100р
5 тетрадей стоят 5*20=100 р 
3  книги стоят 3*100=300 р  всего надо 100+300 р=400 рублей на книги и тетрадь

Answer 2

Problem Analysis

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

Solution

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

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

x + (x + 80) = 120

Simplifying the equation, we get:

2x + 80 = 120

Subtracting 80 from both sides of the equation, we get:

2x = 40

Dividing both sides of the equation by 2, we get:

x = 20

So, the cost of the notebook is 20 rubles.

Now, we need to find the total cost of five notebooks and three books.

The total cost of five notebooks can be calculated as:

5 * x = 5 * 20 = 100 rubles

The total cost of three books can be calculated as:

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

Therefore, the total cost of five notebooks and three books is:

100 + 300 = 400 rubles

So, you need to pay 400 rubles for five notebooks and three books.

Answer

You need to pay 400 rubles for five notebooks and three books.