Redo the company's income statement at the 4,500 unit level of activity using the contribution format Sales in units ... 4,500 Sales revenue... 630,000 cost of goods sold ... 252,000 gross margin .. 378,000 selling and administrative expenses shipping expense .... 56,000 advertising expense ... 70,000 salaries and commissions ... 143,000 insurance expense .... 9,000 depreciation expense .... 42,000 total selling and administrative expenses ... 320,000 net operating income ... 58,000