You left out one big factor, probably one of the biggest ones of all. You forgot to describe the area this person is residing in.
$20,000 can get you by in the cheaper states, and you can live decently enough fine. In fact you can probably buy a home around that range.
$20,000 is chump change in metropolitan and urbanized areas such as but not limited to: LA, WA, SF, Chicago, NYC, LI, etc etc..
But I am guessing your friend is located in one of the bigger cities.
If you live in Massachusetts, make over 26,000 dollars. Impossible to make it 20,000 a year, need to find three roommates to sharing the apartment. Car insurance and taxes are awful high here.