Meaning of ratio: The division of two numbers is called the ratio of these two numbers. 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. Take "3:5=0.5" as an example, "3" is called the former term of the ratio, "5" is called the latter term of the ratio, and "0.5" is called the ratio.

Meaning of proportion: Two expressions with equal proportions are called proportions. Basic properties of proportion: in a proportion, the product of internal terms is equal to the product of external terms, which is called the basic properties of proportion. Take "3: 5 = 6: 10" as an example. "3, 10" is called the external term, and "5,6" is called the internal term.