During a period, $40,000$ units were completed, and $3,500$ units were in ending WIP inventory. Ending WIP was $80\%$ complete for direct materials and $30\%$ complete for conversion costs. What are the equivalent units for direct materials assuming that the weighted$-$average method is used?

$.43,500$

$$ b$.42,800$

$0$ c$.41,050$

$$ d$.34,800$