Schriever Corporation is an oil well service company that measures its output by the number of wells serviced. The company has provided the following fixed and variable cost estimates that it uses for budgeting purposes. Fixed element per month Variable Element por Well Serviced $ 4,500 $ 1.100 $ 600 Revenue Deployee salaries and wages Servicing materials Other expenses $ 57,200 $ 31,000 The planning budget for May was based on 36 wells serviced, but a total of 31 wells were actually serviced in May The activity variance for net operating income for May would have been closest to