budgeting and control

Total production costs for 900 units of output are $58,200 and total production costs for 1,200 units are $66,600. The variable cost per unit is constant up to a production level of 2,000 units per month, but a step up of $6,000 in the monthly total fixed cost occurs when production reaches 1,100 units per month. What is the total cost for a month when 1,000 units are produced?