Opal Ltd manufactures and sells a single product, a wireless doorbell for $50 per unit. Variable costs are $30 per unit and total fixed costs for the current period (2019) are $40,000. Required: a) Calculate the break-even point in units AND in dollars for Opal Ltd. Show all workings. b) Calculate the Margin of Safety in dollars assuming actual sales are $135,000. Show your workings. Briefly comment on your findings regarding Opal Ltd's margin of safety. a) Calculate the sales required in dollars to earn a profit after tax of $15,000. Assume the tax rate is 30%. Show all workings