Question

В классе 25 детей. При посадке деревьев в школьном саду каждая девочка посадила по 2 дерева, а каждый мальчик по 3 дерева. Всего было посажено 63 дерева. Сколько было девочек в классе?

Answer 1

Х -количество девочек

у - количество мальчиков

Составим систему уравнений

х+у=25

2х+3у=63

х= 25-у

2 (25 - у) + 3у=63

50-2у+3у=63

у = 13 - мальчиков

25-13=12 девочек

Проверим 12Х2+13Х3=24+39=63

Answer 2

Problem Analysis

We are given that there are 25 children in the class. Each girl planted 2 trees, and each boy planted 3 trees. In total, 63 trees were planted. We need to determine the number of girls in the class.

Solution

Let's assume there are x girls in the class. Since each girl planted 2 trees, the total number of trees planted by girls would be 2x.

Similarly, the number of boys in the class would be 25 - x. Since each boy planted 3 trees, the total number of trees planted by boys would be 3(25 - x).

According to the given information, the total number of trees planted is 63. Therefore, we can set up the following equation:

2x + 3(25 - x) = 63

Simplifying the equation:

2x + 75 - 3x = 63

-x + 75 = 63

-x = 63 - 75

-x = -12

Multiplying both sides by -1:

x = 12

Therefore, there are 12 girls in the class.

Answer

There are 12 girls in the class.