Sales people can sell cars and try to meet their own annual quota. Administrative employees cannot sell cars. Administrative employees have an annual salary.
Add the following: Sales personnel sell cars. Only one customer can buy any single car. A car is sold by a sales person to a customer.
Add the following: Some sales people supervise other sales people. Some administrative employees supervise other administrative employees. Some administrative employees supervise sales people.
Add the following: Sales personnel have an annual quota. Monthly bonuses are based on meeting the sales person's monthly quota (1/11 of their annual quota). Annual bonuses are based on meeting his/her annual quota.