Hatfield Corporation, which has only one product, has provided the following data concerning its most recent month of operations: Selling price. $123 Units in beginning inventory................ Units produced. Units sold. Units in ending inventory ..... 6,400 6,100 300 Variable costs per unit: Direct materials ... Direct labor.............. Variable manufacturing overhead .... Variable selling and administrative... $45 $30 $1 $8 Fixed costs: Fixed manufacturing overhead......... Fixed selling and administrative....... $140,800 $91,500 What is the net operating income for the month under variable costing? $12,200 $(17,200) $5,600 $6,600