Question

Реши задачу.Книга дороже тетради на 80руб. За книгу заплатили и тетрадь заплатили 120 руб. Сколько нужно заплатить за 3такие тетради и 2такие книги ?

Answer 1

1) пусть тетрадь будет х, тогда книга х+80 . Зная, что за книгу и тетрадь заплатили  120 рублей , составим уравнение. 
х+х+80=120
2х=120-80
2х=40
х=20 (руб) за тетрадь
2) 3х+2(х+80)= 3*20+2( 20+80)=60+200=260 (руб) 
Ответ: 260 рублей надо заплатить 

Answer 2

Problem Analysis

To solve this problem, we need to determine the total cost of purchasing 3 notebooks and 2 books, given that a book is 80 rubles more expensive than a notebook and the total cost of a book and a notebook is 120 rubles.

Solution

Let's assume the cost of a notebook is x rubles. According to the problem, the cost of a book is 80 rubles more than the cost of a notebook. Therefore, the cost of a book is x + 80 rubles.

We are given that the total cost of a book and a notebook is 120 rubles. So we can set up the following equation:

x + (x + 80) = 120

Simplifying the equation, we get:

2x + 80 = 120

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

2x = 40

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

x = 20

Therefore, the cost of a notebook is 20 rubles, and the cost of a book is 20 + 80 = 100 rubles.

To find the total cost of purchasing 3 notebooks and 2 books, we can multiply the cost of a notebook by 3 and the cost of a book by 2, and then add the results:

Total cost = (cost of a notebook * 3) + (cost of a book * 2)

Substituting the values we found earlier, we get:

Total cost = (20 * 3) + (100 * 2) = 60 + 200 = 260 rubles

Therefore, the total cost of purchasing 3 notebooks and 2 books is 260 rubles.

Answer

The total cost of purchasing 3 notebooks and 2 books is 260 rubles.