In a process with 720 units of beginning Work in Process, the company completed and transferred out 10900 units during a period. There were 4500 units in the ending Work in Process that were 60% completed as to conversion costs. Materials are added 80% at the beginning of the process and 20% when the units are 90% complete. How much is equivalent units of production for the period for material costs if the weighted-average method is used?

Can you also explain what is meant when they say "materials are added at x point in the process"