answer is -140000. please show work for how to get answer.

The actual information pertains to the month of August. As part of the budgeting process, Alloway's Fencing Company developed the following static budget for August. Alloway is in the process of preparing the flexible budget and understanding the results. Actual Results Flexible budget Static Budget 6,000 Sales Volume (in 8,500 units) Sales $321,500 Revenue 336,000 Direct materials $68,300 67,200 Direct labor 97,400 100,800 VMOH 44,800 42,000 58,000 Fixed Costs 57,500 Operating income 68,000 What is the sales volume variance for revenue? (If the variance is favorable, you answer should be negative) er -140,000