Stonebraker Corporation has provided the following contribution format income statement for sales of 9,000 units: Sales Variable expenses Contribution margin Fixed expenses Net operating income $270,000 189,000 81,000 77,400 3,600 1. If sales increase to 9,040 units, what would be the estimated increase in net operating income? 2. If the variable cost per unit increased by $6, spending on advertising increased by $3,000 and unit sales increase by 19,200 units, what would be the estimated net operating income? 3. Estimate how many units must be sold to achieve a target profit of $26,100