Dividing two numbers is called ratio, and the obtained value is called quotient. For example, in A: B, A is the former term of the ratio, B is the latter term of the ratio, and the quotient obtained by a÷b is called the ratio of A: B.

The nature of the ratio: the former term of the ratio and the latter term of the ratio are multiplied or divided by the same number (except 0), and the ratio of this ratio remains unchanged.

First of all, the meaning of ratio, the names of various parts of ratio, the basic nature of ratio, the relationship between ratio and fraction and division,

Application of ratio.

Proportion application problem: 1. Find out the number of copies first, then how many copies of the total, and use the total and how many copies of the total to find out the amount of each copy. Or multiplied by the score corresponding to each part.

Problem solving skills:

When A:B= 1:2, the inner product is equal to the outer product.

So 2A=B

When a = 1, cross multiplication.

So 2A=B

When A:B= 1:2, you can also use the parameter: let each copy be k.

So a = 2 k.

B=K