Answer:
Discretionary income
Explanation:
Discretionary income can be described as the amount of money that an individual have left to save, spend, or invest after he has paid taxes and for necessities.
The necessities are food, clothing and shelter which are the most important needs of human beings.
Discretionary income is therefore spent on vacations, luxury goods, and other commodities that are not essential.
Therefore, the $2,800 left over for the Johnsons is their discretionary income.