ok, realistic (in my area) living expenses for 2 people only 1 works with a single car.
car inurance - $30/month car insurance (10 y.o. car)
gas - $100/month.
rent - $600 single bedroom with heat/hot water.
electric - $60
internet+phone - $60
food - $600/month ($3/meal + $1snack per day per person)
toiletries - $50/month
emergency fund - $200/month
total needed per year - $20,400
granted I know that rent in my area can be cheap, and insurance on my car is low because it is so old (in fact, the number I used included my motorcycle insurance ) and we have cheap insurance in general.
Food estimates are a tiny bit high, as I know you can eat for cheaper than that, but that is about what I spend and I get tasty food. Some meals are less expensive so it all balances out.
I tried to estimate for medical expenses and car repairs and other general needs. Of course this budget doesn't allow for any luxuries and you better already own all your clothes
If you earn $20k/year I'm not sure if you get taxed or not so obviously you need to earn more than what I stated, but $30k should cover it. In fact at $30k you should be able to save up for another car once the current one breaks down plus be able to entertain yourself for cheap. Of course, if you racked up a huge college debt, then you'll be screwed.