Mathematical ratio refers to the division of two numbers, also called the ratio of two numbers. It is a new relationship between two related quantities.
Such as rectangle, aspect ratio. The ratio of the price of purchased goods to the quantity of purchased goods.
Similar related quantities, if their proportion is certain, then they form a proportion.
Proportion is widely used, for example, engineers draw architectural drawings, and they will enlarge or reduce a certain proportion according to the proportion of physical data. Draw it on the map. Then objects of different sizes but the same shape appeared.