Question

Помогите с задачей : у трёх девочек вмести было 20 карандашей. у Тани и Юли вмести было 15 карандашей. у Юли и Светы вмести 12 карандашей. Сколько карандашей у каждой девочки( напишите решение и ответ)

Answer 1

1)20-15≈5(к)-было у Светы
2)12-5≈7(к)-было у Юли
3)15-7≈8(к)-было у Тани
Ответ:7 к.,5 к.,8 к.,

Answer 2

Problem Analysis

We are given the information that there are three girls, and the total number of pencils they have together is 20. Additionally, we know the number of pencils each pair of girls has together. We need to find out how many pencils each girl has individually.

Solution

Let's assign variables to represent the number of pencils each girl has: - Let T represent the number of pencils Tanya has. - Let Y represent the number of pencils Yulia has. - Let S represent the number of pencils Svetlana has.

From the given information, we can form the following equations: 1. T + Y + S = 20 (equation 1) 2. T + Y = 15 (equation 2) 3. Y + S = 12 (equation 3)

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

Subtracting equation 3 from equation 1, we get: (T + Y + S) - (Y + S) = 20 - 12 T = 8 (equation 4)

Substituting equation 4 into equation 2, we get: 8 + Y = 15 Y = 7 (equation 5)

Substituting equation 5 into equation 3, we get: 7 + S = 12 S = 5 (equation 6)

Therefore, Tanya has 8 pencils, Yulia has 7 pencils, and Svetlana has 5 pencils.

Answer

Tanya has 8 pencils, Yulia has 7 pencils, and Svetlana has 5 pencils.