I'll use the numbers you posted ($20k in CC debt, ability to pay it off if there were no interest in 24 months) and I'll assume she is pauying 30% interest on those cards. Thus, she can afford to pay $833/month and the interest is $500/month. My conclusion: this isn't a big enough problem to warrant bankruptcy. If she stopped using the credit cards and paid $833/month she'd be CC debt free in 38 months (even at 30% interest rates).
I don't know man. I live in a relatively inexpensive city and there's still no way this could happen. She has $20,000 debt, simple interest of 30% would be $6000
interest per year. That's about $500 per month just for the interest, as you've already stated. Let's look at the monthly budget.
$20,000 per year is $1,666 per month:
-$700 to rent a studio/bachelor apartment in the ghetto
-$200 for food, soap, toilet paper, etc
-$500 interest payment
-$50 phone bill (good luck living without a telephone)
-$84 bus pass (that's what they cost in my city, but it's cheaper than a car)
=$132 to pay off the debt
Let's just keep it simple and ignore a few factors. $20,000 debt / $132 payment = 151 months. That's
12 years to pay off the debt. Fuck this bullshit. File for bankruptcy and call it a day.