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Required information [The following information applies to the questions displayed below.] Donaldson Company's contribution format income statement for the most recent month is shown below: The company sold 40,000 units in its most recent month and its relevant range of production is 30,000 to 50,000 units. Click here to download the Excel template, which you will use to answer the questions that follow. Click here for a brief tutorial on Goal Seek in Excel. Click here for a brief tutorial on SOLVER in Excel. Click here for a a brief tutorial on Charts in Excel. Required: 1. In the Excel file: a. How is the contribution margin shown in cell B14 being calculated? b. How is the net operating income shown in cell B16 being calculated? c. How is the net profit margin percentage shown in cell B18 being calculated? d. How is the contribution margin ratio shown in cell D14 being calculated? e. How is the break-even sales shown in cell G12 being calculated? Will the amount shown in cell G12 change if unit sales change and all else holds constant? f. How is the margin of safety percentage in cell G14 being calculated