Folsom Fashions sells a line of women's dresses. The company uses flexible budgets to analyze its performances. The firm's performance report for November is presented below: Actual Budget Dresses sold 5,000 6,000 Sales $ 235,000 $ 300,000 Variable costs 145,000 180,000 Contribution margin $ 90,000 $ 120,000 Fixed costs 84,000 80,000 Operating income $ 6,000 $ 40,000 What additional information would be needed for Folsom to calculate the dollar impact of changes in market share on November's operating income