a year to live in this neighborhood.
mary's making twenty so mary has $1,000 in disposable income at the end of the year or throughout the year. mark, on the other hand, who's making $40,000 - mary's making $20,000 - now most people would say mark makes twice as much as mary because he makes $40,000 whereas she makes $20,000, right?
he's actually making 21 times as much as mary because both of them have to spend $19,000 to live in the neighborhood. after that, "money" is spent. and that's not really money, that is cost of living, right, after the basic core costs are covered. mary has $1,000 left over, mark 