7-23 Flexible-budget preparation and analysis. XYZ Printers, Inc., produces luxury checkbooks with three checks and stubs per page. Each checkbook is designed for an individual customer and is ordered through the customer's bank. The company's operating budget for September 2017 included these data: Number of checkbooks Selling price per book 20,000 $ 22 Variable cost per book $ 9 Fixed costs for the month $150,000 The actual results for September 2017 were as follows: Number of checkbooks produced and sold Average selling price per book Variable cost per book Fixed costs for the month 15,000 $ 23 $ 8 $155,000 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. As the company's management accountant, you have been asked to provide explanations for the disappointing September results. XYZ develops its flexible budget on the basis of budgeted per-output-unit revenue and per-output-unit variable costs without detailed analysis of budgeted inputs.