Food and rent /are/ also subtracted from gross income to calculate discretionary income; I was highlighting those two items, not defining ‘discretionary income’, which already has a fairly well-established meaning.
Discretionary income is a complex concept that can hide many premises. I order to fully define it, you need to know how much/what quality of food, housing, and health care are discretionary. (If you would find such a classification useful, don’t try to specify each case separately; determine the rule that you use to make such choices.)
You asked what you did wrong here so I’m going to point out one little thing.
Why health care? Why not, say, food or rent? There are tons of unmentioned premises here.
Food and rent /are/ also subtracted from gross income to calculate discretionary income; I was highlighting those two items, not defining ‘discretionary income’, which already has a fairly well-established meaning.
Discretionary income is a complex concept that can hide many premises. I order to fully define it, you need to know how much/what quality of food, housing, and health care are discretionary. (If you would find such a classification useful, don’t try to specify each case separately; determine the rule that you use to make such choices.)