Equivalent Units of Materials Cost

The Rolling Department of Kraus Steel Company had $2,500$ tons in beginning work in process inventory $(80\%$ complete$)$ on October $1.$ During October, $42,100$ tons were completed. The ending work in process inventory on October $31$ was $2,100$ tons $(30\%$ complete$).$

What are the total equivalent units for direct materials for October if materials are added at the beginning of the process?