Why are these two questions calcultaed differently? One is calculated (new total sales*Cm Ratio) - Fixed Expenses and the other is calculated increase in sales*cm ratio. Why? help

Required: (Consider each case independently): 1. What would be the revised net operating income per month if the sales volume increases by 50 units? 2. What would be the revised net operating income per month if the sales volume decreases by 50 units? 3. What would be the revised net operating income per month if the sales volume is 7,600 units? Explanation 1. The revised net operating income would be: Required information [The following information applies to the questions displayed below.] Raner, Harris and Chan is a consulting firm that specializes in information systems for medical and dental clinics. The firm has two offices-one in Chicago and one in Minneapolis. The firm classifies the direct costs of consulting jobs as variable costs. A contribution format segmented income statement for the company's most recent year is given: By how much would the company's net operating income increase if Minneapolis increased its sales by $75,000 per year? Assume change in cost behavior patterns