Process Costing

A company operates a process costing system using FIFO method of valuation. No losses occur in the process.All materials are input at the commencement of the process.Conversion costs are incurred evenly through the process. The following data relate to last period: Opening WIP -2,000 units , 60% of degree completion Total no of units completed -14,000 units Closing WIP -3,000 units , 30% of degree completion Costs arising: Materials - $51,000 Conversion- $193,170 what was the value of the closing WIP for the last period ? So,according to the answer given , Material cost per unit = [51,000 ÷ (12,000 + 3,000)] = $3·40 Conversion: Cost per equivalent unit = [193,170 ÷ (12,000 + 0·40 × 2,000 + 0·30 × 3,000)] = 193,170 ÷ 13,700 = $14·10 Closing inventory valuation = (3,000 × 3·40) + (900 × 14·1) = $22,890 I got right with my calculation except for the calculation of material cost per unit which is $3.40. My calculation is $51,000/13,700. I need your help sir .