The accountant at John's Cycle Manufacturing Company uses the weighted$-$average costing method. The accountant reported that there were $400$ equivalent units of work completed to date, and reported the following cost:

Summary of Total Costs

Beginning work in progress $($direct materials, $$15,000+$ conversion costs $$6,000)$ $$21,000$

Costs added during March $($direct materials, $$12,000+$ conversion costs $$18,000$ $$30,000$

Total costs to account for in March $$51,000$

Required: Compute the conversion cost$-$per$-$unit using the weighted$-$average costing method.