a) What is the sales volume variance for operating income?

b) What is the flexible budget variance for operating income?

RTI company's master budget calls for production and sale of 18,000 units for $81,000; variable costs of $30,600; and fixed costs of $20,000. During the most recent period, the company incurred $32,000 of variable costs and $28,000 of fixed costs to produce and sell 20,000 units for $85,000