In September, Numbers Incorporated sold 45,000 units of its only product for $438,000, and incurred a total cost of $405,000, of which $43,000 was fixed costs. The flexible budget for September showed total sales of $480,000. Among variances of the period were: total variable cost flexible-budget variance, $8,000U; total flexible-budget variance, $75,000U; and, sales volume variance, in terms of contribution margin, $45,000U. The budgeted fixed cost for September was: Multiple Choice $18,000. $51,000. $83,000. $108,000.