Question

Число ног у кроликов и кур-72 а число голов 25. Сколько всего кур? (с решением)

Answer 1

Пусть х - куры, тогда (25 - х) - кролики. У кур 2х ног, у кроликов 4 * (25 - х) ног. Всего 72 ноги. Уравнение:
2х + 4 * (25 - х) = 72
2х + 100 - 4х = 72
2х - 4х = 72 - 100
- 2х = - 28
х = - 28 : (-2)
х = 14
Ответ: 14 кур.

Answer 2

Problem Analysis

We are given that the total number of legs of rabbits and chickens is 72, and the total number of heads is 25. We need to find the total number of chickens.

Solution

Let's assume the number of rabbits is x and the number of chickens is y.

From the given information, we can form the following equations: 1. The total number of legs: 4x + 2y = 72 2. The total number of heads: x + y = 25

We can solve these equations simultaneously to find the values of x and y.

Solving the Equations

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

Multiplying equation 2 by 2, we get: 2(x + y) = 2(25) 2x + 2y = 50

Now, we can subtract equation 1 from this new equation: (2x + 2y) - (4x + 2y) = 50 - 72 -2x = -22 x = 11

Substituting the value of x into equation 2, we get: 11 + y = 25 y = 25 - 11 y = 14

Answer

The total number of chickens is 14.

Verification

Let's verify our answer using the given information.

The total number of legs of rabbits and chickens is 72. Since rabbits have 4 legs and chickens have 2 legs, we can calculate the total number of legs as follows: 4 * x + 2 * y = 72 4 * 11 + 2 * 14 = 44 + 28 = 72

The total number of heads is 25, which matches the given information.

Therefore, our answer of 14 chickens is correct.

Conclusion

The total number of chickens is 14.