The correct answer is: "Purchasing Power Parity"
The theory of the Purchasing Power Parity is used to compare the cost of life and living standards between two countries that use two different currencies. This is done by comparing two curriencies through a basket of goods, by comparing their market prices and, therefore, how they are valued under each currency. This enables to conclude how much of each currency you need to purchase an specific product (a bike) and hence, the purchasing power of consumers who hold that currency.