To increase production beyond the current level of 10,000 units, Melville Corporation must lease additional equipment and pay overtime premiums to its employees. At the present level of operations of 10,000 units, fixed costs total $50,000 and variable costs are $3 per unit. If Melville incurs an additional $20,000 in fixed costs, they can produce and sell an additional 10,000 units at a variable cost of $5 each. Management policy forbids expanding capacity unless unit average cost remains constant.

How many units must Melville produce and sell to maintain the same average cost as at 10,000 units?