In January of the current year, Mrs. Black purchased an office building and used office furnishings. The used office furnishings consisted of chairs, desks, and file cabinets. Of the purchase price, $900,000 was allocated to the office building and $50,000 was allocated to the used office furnishings. According to the General Depreciation System (GDS) under MACRS for depreciation, what recovery period must she use for the purchased items