Question

Книга, альбом и тетрадь вместе стоят 78 копеек. Книга и альбом стоят 60 копеек, а книга и тетрадь 41 копейку. Сколько стоит каждый предмет отдельно? (решение)

Answer 1

Problem Analysis

We are given the total cost of a book, an album, and a notebook, as well as the individual costs of the book and album, and the book and notebook. We need to determine the cost of each item separately.

Solution

Let's assign variables to the cost of the book, album, and notebook, respectively. We'll use the following variables: - Cost of the book: B - Cost of the album: A - Cost of the notebook: N

From the given information, we have the following equations: 1. B + A + N = 78 (The total cost of the book, album, and notebook is 78 kopeks) 2. B + A = 60 (The cost of the book and album is 60 kopeks) 3. B + N = 41 (The cost of the book and notebook is 41 kopeks)

To solve this system of equations, we can use substitution or elimination. Let's use the elimination method.

Subtracting equation 3 from equation 1, we get: (B + A + N) - (B + N) = 78 - 41 Simplifying, we have: A = 37

Now, we can substitute the value of A into equation 2: B + 37 = 60 Simplifying, we have: B = 23

Finally, we can substitute the values of B and A into equation 1 to find the value of N: 23 + 37 + N = 78 Simplifying, we have: N = 18

Therefore, the cost of the book is 23 kopeks, the cost of the album is 37 kopeks, and the cost of the notebook is 18 kopeks.

Answer

The cost of each item separately is as follows: - Book: 23 kopeks - Album: 37 kopeks - Notebook: 18 kopeks