It is called Direct proportion as it's one quantity is increased other also increases.

Direct Proportion:
When one quantity increases, the other quantity also increases in direct proportion, meaning the ratio between them remains constant. This type of proportion is called direct proportion.

Explanation:
In direct proportion, as one quantity increases, the other quantity increases by the same factor or ratio. The two quantities are directly related to each other. Let's understand this with an example:

Suppose we have a car that travels at a constant speed of 60 km/h. If we increase the time of travel, the distance covered by the car will also increase in direct proportion.

Example:
Let's consider the time of travel and the distance covered by the car:
- If the car travels for 1 hour, it will cover a distance of 60 km.
- If the car travels for 2 hours, it will cover a distance of 120 km.
- If the car travels for 3 hours, it will cover a distance of 180 km.

As we can see, the distance covered by the car is directly proportional to the time of travel. The ratio between the distance and time remains constant, which is 60 km/h.

Key Points:
- Direct proportion is a relationship between two quantities where an increase in one quantity leads to an increase in the other quantity.
- The ratio between the two quantities remains constant in direct proportion.
- In direct proportion, as one quantity increases, the other quantity increases by the same factor or ratio.
- The symbol for direct proportion is ":" or "=".
- The equation for direct proportion is y = kx, where "y" and "x" are the two quantities and "k" is the constant of proportionality.

Conclusion:
When one quantity increases, the other quantity also increases in direct proportion. Direct proportion is a fundamental concept in mathematics and is widely used in various real-life situations. Understanding direct proportion helps in solving problems related to ratios, rates, and proportions.