First, multiple methods

The number of roosters is three times that of hens, that is, the number of roosters is twice that of hens, and because there are 18 roosters, the number of hens is 18÷2=9, and the number of roosters is three times that of hens, that is, 27 hens.

Second, the equation method

Suppose: the number of hens is X, and the number of cocks is 3X.

3X-X= 18

2X= 18

X=9

Answer: There are 9 hens and 27 cocks.

Expand data 1. Solution method of linear equation with one variable

1. There are five steps in solving a linear equation, namely, removing the denominator, removing brackets, moving terms, merging similar terms, and converting them into 1. All steps are carried out according to the properties of algebraic expressions and equations.

2. In a one-dimensional linear equation, the denominator removal step is usually multiplied by the least common multiple of each denominator. If the denominator is a fraction, it can be converted into the form that the other parts of the item are multiplied by the reciprocal of the fraction on the denominator.

Second, examples

There are several chickens and rabbits in a cage, counting from the top, 35 heads, counting from the bottom, 94 feet. How many chickens and rabbits are there in each cage?

Solution: For every X rabbits, there are (35-x) chickens.

4X+2(35-X)=94

4X+70-2X=94

2X=94-70

X= 12

A: The number of chickens is 12 and the number of rabbits is 23.

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