Ratio is a quantitative relationship, just like division and fraction, but division is an operation and fraction is a number, which is their difference. The ratio consists of two numbers, the first number is called the former item, the second number is called the latter item, and the middle is connected by ":",and the latter item cannot be 0.

Division of two numbers is also called the ratio of two numbers. ":"is a comparative symbol. In the ratio of two numbers, the number before the comparison sign is called the first term of the ratio, and the number after the comparison sign is called the last term of the ratio. The quotient obtained by dividing the former term by the latter term is called the ratio. The ratio is usually expressed in fractions, and can also be expressed in decimals or integers. The basic nature of the ratio: the first and last items of the ratio are multiplied or divided by the same number at the same time (except 0), and the ratio remains unchanged.

Such as the proportion in life:

Wang defeated his opponent in the world table tennis championship with 1 1:7.

Another example is:

The circumference of a right triangle is 24 cm, and the ratio of three sides is 3:4:5.

Meaning: Divide a right triangle with a circumference of 24CM into ten parts, with three sides occupying three parts, four parts and five parts in turn;

Another example is that the ratio of gold to silver in the alloy is 2:3.

Meaning: Divide the total amount of alloy into five parts, with gold and silver accounting for two and three parts respectively.