Price Relative Calculation
The price relative is a measure used to compare the price of a commodity in different periods with a base year. It is calculated by dividing the price of the commodity in the given year by the price of the commodity in the base year and multiplying the result by 100.

Formula for Price Relative Calculation
Price Relative = (Price in Given Year / Price in Base Year) * 100

Calculation of Price Relative
Given, the price of a commodity in the year 1975 is 25 and the price of the same commodity in the year 1980 is 30. Taking 1975 as the base year, the price relative in 1980 can be calculated as follows:

Price Relative = (Price in 1980 / Price in 1975) * 100
Price Relative = (30 / 25) * 100
Price Relative = 120

Therefore, the price relative in the year 1980 with 1975 as the base year is 120.

Interpretation of Price Relative
The price relative of 120 indicates that the price of the commodity in the year 1980 was 120% of the price of the same commodity in the base year 1975. It also shows that the price of the commodity has increased by 20% from 1975 to 1980.

Conclusion
The price relative is an important measure used to compare the prices of commodities in different periods. It helps to understand the changes in the prices of commodities and their impact on the economy. In this case, the price relative of 120 indicates that the price of the commodity has increased by 20% from 1975 to 1980.

Price relative =(p1/p0)×100
=(30/25)×100
=120