4. Confirm your calculations in Requirement 3 above by increasing the unit sales in your worksheet by 20% so that the Data area looks like this: A 1 Chapter 5: Applying Excel B 2 3 Data 4 Unit sales 60,000 units 5 Selling price per unit $ 20 per unit 6 Variable expenses per unit $ 8 per unit 7 Fixed expenses $ 450,000 (a) What is net operating income? (Negative amount should be indicated by a minus sign.) Net operating income (loss) (b) By what percentage did the net operating income increase? Percentage increase in net operating income %