Answer: The commission is paid according to sales amounts that are likely to vary from month to month.
Step-by-step explanation: Instead of a salary that is paid in the same amount on a schedule, the commission may be very large one month and very small or zero at other times.
Financial planning usually includes monthly payments that and predictable expenses for food, transportation, utilities, etc. The person who earns a commission must remember to set aside some of the "extra" to cover these expenses. And be prepared to work more or harder at some times to make sales when they don't come easily.