n September, Numbers Incorporated sold 41,500 units of its only product for $405,000, and incurred a total cost of $375,000, of which $40,000 was fixed costs. The flexible budget for September showed total sales of $450,000. Among variances for the period were: total variable cost flexible-budget variance, $9,500U; total flexible-budget variance, $78,000U; and, sales volume variance, in terms of contribution margin, $42,000U.

The master budget operating income for September was