A train service carries $20,000$ people daily between Rationalia and Real City. The rail line could serve up to $31,000$ people. The cost to ride the train is $ $\backslash$pi $,$ but research shows that for each fare increase of $$0\mathrm{.}02,$ ridership will go down by $271$ people.

Create a function to represent the revenue of the train service after x increases of $$0\mathrm{.}02.$