Final answer:
A fixed expense is one with a constant amount, while a variable expense is one with an amount that varies. Discretionary spending is the most flexible budget item and can be easily changed.
Step-by-step explanation:
A fixed expense is one for which the amount does not change and it should be considered a constant in the budget. An example of a fixed expense is the rent on a factory or retail space. The amount of fixed expenses remains the same regardless of the level of production.
A variable expense is one for which the amount varies and it should be considered flexible in the budget. An example of a variable expense is cost of raw materials for production. The amount of variable expenses changes depending on the level of production.
Discretionary spending is the most flexible budget item and the easiest to change. It includes expenses like entertainment and personal care items. You have control over the amount spent on discretionary expenses.