Question

Боря купил 4 книги. Все книги без первой стоят 42р., без второй-40р., без третьей- 38р., без четвертой-36р. Сколько стоит каждая книга? Подскажите пожалуйста условие и решение

Answer 1

Нужно эту задачу решить чисто арифметически. Здесь в каждом условии в сумму цен книг не входит только одна цена. А если сложить все эти числа, то получим утроенную сумму цен книг. Значит сумма цен книг будет (42+40+38+36)/3=52. 
Теперь легко найти цены книг. 
Первая 52-42=10 
Вторая 52-40=12 
Третья 52-38=14 
Четвертая 52-36=16

Answer 2

Problem Statement:

Borya bought 4 books. The price of all the books without the first one is 42 rubles, without the second one is 40 rubles, without the third one is 38 rubles, and without the fourth one is 36 rubles. We need to find the price of each book.

Solution:

Let's assume the price of the first book is x rubles.

According to the given information, the price of all the books without the first one is 42 rubles. So, the sum of the prices of the second, third, and fourth books is 42 rubles.

Similarly, the sum of the prices of the first, third, and fourth books is 40 rubles, and the sum of the prices of the first, second, and fourth books is 38 rubles.

Finally, the sum of the prices of the first, second, and third books is 36 rubles.

We can set up the following system of equations to solve for the price of each book:

x + (x + 2) + (x + 4) = 42 (x + 2) + (x + 4) + (x + 6) = 40 (x + 2) + x + (x + 4) = 38 x + (x + 2) + (x + 4) = 36

Simplifying each equation, we get:

3x + 6 = 42 3x + 12 = 40 3x + 6 = 38 3x + 6 = 36

Solving these equations, we find:

x = 12

Therefore, the price of each book is as follows: - The first book costs 12 rubles. - The second book costs 14 rubles. - The third book costs 16 rubles. - The fourth book costs 18 rubles.

Please note that the solution assumes a linear relationship between the prices of the books.