The executive vice president of the company observed that the operating income for September was much lower than anticipated, despite a higher-than-budgeted selling price and a lower-than-budgeted variable cost per unit. The manager is threatening to withhold year-end bonuses unless an explanation is presented. As the companys management accountant, you have been asked to provide explanations for the disappointing September results. How can the data be presented to show that the managers did control the costs that were controllable?