The rent was $550 a month, utilities not included, the going rate in 2008 for a two-bedroom unit in one of the worst neighborhoods in America’s fourth-poorest city. Arleen couldn’t find a cheaper place, at least not one fit for human habitation, and most landlords wouldn’t rent her a smaller one on account of her boys. The rent would take 88 percent of Arleen’s $628-a-month welfare check.