The static budget, at the beginning of the month, for Keats Company follows: Static budget: Sales volume: 2,100 units: Sales price: $52 per unit Variable costs: $12.50 per unit: Fixed costs: $25,500 per month Operating income: $57,450 Actual results, at the end of the month, follows: Actual results: Sales volume: 1,900 units: Sales price: $60 per unit Variable costs: $16 per unit: Fixed cost: $39,000 per month Operating income: $44,600 Calculate the sales volume variance for operating income. $200 F $7,900 F $7,900 U $4,950 U