Birch Company normally produces and sells 45,000 units of RG-6 each month. RG-6 is a small electrical relay used as a component part in the automotive industry. The selling price is $49 per unit, variable costs are $21 per unit, fixed manufacturing overhead costs total $228,000 per month, and fixed selling costs total $306,000 per month. Employment-contract strikes in the companies that purchase the bulk of the RG-6 units have caused Birch Company's sales to temporarily drop to only 12,000 units per month. Birch Company estimates that the strikes will last for two months, after which time sales of RG-6 should return to normal. Due to the current low level of sales, Birch Company is thinking about closing down its own plant during the strike, which would reduce its fixed manufacturing overhead costs by $68,000 per month and its fixed selling costs by 11%. Start-up costs at the end of the shutdown period would total $12,000. Because Birch Company uses Lean Production methods, no inventories are on hand. At what level of sales (in units) for the two-month period should Birch Company be indifferent between closing the plant or keeping it open