BET Inc. sells two types of cell phones. The following is BET's sales information: a. Calculate the weighted average contribution margin per unit. b. How many units must be sold to break even? c. How many Units of each product must be sold to break even? d. How many units in total must be sold to earn a monthly profit of $180,000? e. How many units of each product must be sold to earn a monthly profit of $180,000? Do a separate calculation to: a. Calculate the weighted average contribution margin ratio. b. Find the break-even point in sales dollars. c. Find the amount of sales dollars required to earn a monthly profit of $540,000? d. Assume the contribution margin income statement prepared in requirement a is the company's base case. What is the margin of safety in sales dollars