a. Based on the weighted-average contribution margin per unit that reflects the current production/sales plan (which you used above in Question 3), what is the breakeven point, expressed both in terms of total SAMs (standard allowed minutes) and in terms of total output (units produced), for the SEWMEX factory as a whole? Show your calculations. (Hint: to derive the breakeven point, use the equation for pre-tax profit, T, that you developed in response to Question 3a above. Since revenues are expressed in U.S. dollars and because the dollar is the more stable currency, base all breakeven- point calculations in dollars.) Any assumptions made in your calculations should be noted. b. Based on a weighted-average contribution margin ratio, which reflects the current production/sales plan (Table 2), what is the breakeven point in dollars for the SEWMEX factory as a whole? Show calculations. c. Use the Solver routine in Excel to solve for the overall breakeven point (in total units of product per month, X), given the current production/sales plan (Table 2). d. Based on the production/sales mix reflected in case Table 2, derive product-line breakeven points (in units per month and in dollars per month).