Seventy-Two Inc., a developer of radiology equipment, has stock outstanding as follows: 60,000 shares of cumulative preferred 3% stock, $20 par and 410,000 shares of $25 par common.During its first four years of operations, the following amounts were distributed as dividends: first year, $33,000; second year, $75,000; third year, $100,000; fourth year, $120,000