# Proportional Relationship

**Proportional Relationship** means equivalency between two variables that relate to each other and maintain a set proportion. Also called the “Relation of Proportionality,” it is a mathematical term that explains how two variables relate when they do so in equivalence.

When the two varying quantities are in a relation of proportionality, they are multiplicatively connected to a constant in nature. These two variables are directly proportional to one other, meaning they might increase or decrease but the set ratio stays the same.

**The Mathematical Formula of Proportional Relationship**

The formula to calculate the relation of proportionality is given below -

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** k = x / y**

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(Here, **k** is the constant variable or constant of proportionality, whereas y and x are proportional to each other.)

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**For example**, Laine is going to the market to buy some chocolates. Now, the price of the chocolate is $1, which we can count as the constant - **k**. The number of chocolates she's going to buy is "x".

If she increases or decreases the number of chocolates to purchase (x), the total cost (y) also increases constantly. Hence, the constant** k** is the proportional relationship between the variables - **x** and **y**.

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**Use of the Term in Sentences**

- The proportional relationship is a mathematical term that indicates two or more variables.
- The proportional relationship is used to understand how an increase or decrease in one variable affects the other.
- The proportional relationship is often visually demonstrated with line graphs to increase the ease of understanding.