Absorption and marginal costing

Cost and selling price details for product Z are as follows. Direct materials : $ 6 per unit Direct labour : $ 7.50 per unit Variable overhead : $ 2.50 per unit Fixed overhead absorption rate : $ 5.00 per unit Selling price : $ 30 per unit Budgeted production for the month was 5,000 units although the company managed to produce 5,800 units, selling 5,200 of them and inncurring fixed overhead costs of $ 27,400 What is the marginal costing profit for the month?? My answer Sales (5,200 x $ 30 = $ 156,000) - Variable production cost (5,800 x $ 16 = $ 92,800) - FIxed overhead $27,400 = $ 35,800 Actual answer Sales (5,200 x $ 30 = $ 156,000) - Variable production cost (5,200 x $ 16 = $ 83,200) - FIxed overhead $27,400 = $ 45,400 Dear sir, may i ask actually variable production cost is multiply by sales units ?