Value of money (incomes) question - what is the "r" here?
This question implies to me that you want to convert historical incomes to “2020 dollars”. The standard way to do that is to use the consumer price index (CPI). Note that this is the level, not the rate of change (“inflation rate”).

The formula for a year T is straightforward:

(Income in “2020 dollars”) = (income in year T) *(CPI index in 2020)/(CPI in year T).

For example, if the income was \$100 in a year where the CPI was 60, and the 2020 CPI is 110, the income in 2020 dollars is \$100*(110/60).

If you wanted to convert future incomes to 2020 dollars, you would need to create an assumed inflation rate. You would either use the PV formula, or use the above formula with an extrapolated CPI. How the future inflation rate is determined is your decision.