Reex Chemical Company manufactures Compound A in two sequential departments. On June 1, Department 2 had 3000 units, which were 50 per cent complete as to conversion cost. During June, 15 000 units were completed and transferred from Department 1. On June 30, Department 2 had 4000 units, which were 20 per cent complete as to conversion costs. How many units were completed and transferred from Department 2 during the month of June?