KöMaL 2022 K746

In a certain small country, citizens are charged for gas consumption as follows: in the first year of the new regulations, the first 1700 m${}^3$ of gas costs 100 pennies/m${}^3$, and any further consumption costs 750 pennies/m${}^3$. From the following year onwards, the quantity sold for the reduced price is determined each year from the nationwide average consumption of the previous year. John Average lives in this country, and he used gas with these conditions for a year. Then he realized that he was paying too much, and decided to economise with the gas used in his household. He succeeded in reducing his consumption by 10% in the following year. However, since everyone was trying to save money, the mean consumption decreased by 15%. Although John Average used less gas than previously, he still had to pay more (for the whole year) than in the previous year. What may have been John's consumption during the first year?