Question

Школьники класса из 30 человек сажали деревья. Каждый мальчик посадил по 5 деревьев, а каждая девочка - по 3 дерева. Сколько мальчиков и сколько девочек в классе, если всего посадили 122 дерева?

Answer 1

Забей в Г Д З. там точно найдёшь. Ну а если её сам учитель придумал, то попроси помощи у взрослых. Удачи!

Answer 2

Problem Analysis

We are given that a class of 30 students planted trees, with each boy planting 5 trees and each girl planting 3 trees. The total number of trees planted is 122. We need to determine the number of boys and girls in the class.

Solution

Let's assume there are x boys in the class and y girls in the class.

According to the given information, each boy planted 5 trees and each girl planted 3 trees. So, the total number of trees planted by boys would be 5 times the number of boys (5x), and the total number of trees planted by girls would be 3 times the number of girls (3y).

We are also given that the total number of trees planted is 122. Therefore, we can write the equation:

5x + 3y = 122 We also know that the total number of students in the class is 30. So, we can write another equation:

x + y = 30 Now, we have a system of two equations with two variables. We can solve this system to find the values of x and y.

Solving the System of Equations

We can solve the system of equations using substitution or elimination method. Let's use the elimination method.

From equation we can rewrite it as:

x = 30 - y

Substituting this value of x in equation we get:

5(30 - y) + 3y = 122

Simplifying the equation:

150 - 5y + 3y = 122

-2y = -28

Dividing both sides by -2:

y = 14

Substituting this value of y in equation we get:

x + 14 = 30

x = 30 - 14

x = 16

Answer

Therefore, there are 16 boys and 14 girls in the class.

Verification

To verify our answer, let's check if the total number of trees planted by boys and girls matches the given information.

Total number of trees planted by boys = 5x = 5 * 16 = 80 trees

Total number of trees planted by girls = 3y = 3 * 14 = 42 trees

Total number of trees planted = 80 + 42 = 122 trees

The total number of trees planted matches the given information, so our answer is correct.

Conclusion

There are 16 boys and 14 girls in the class.