DALLAS company's sales and expenses for last month follow: Total Per Unit Sales $ 632,000 $ 40 Variable expenses 442,400 28 Contribution margin 189,600 $ 12 Fixed expenses 146,400 Net operating income $ 43,200 Required: 1. What is the monthly break-even point in unit sales and in dollar sales? 2. What is the total contribution margin at the break-even point? 3. How many units would have to be sold each month to earn a target profit of $63,600? Show calculations. 4. Assume that the tax rate is 30%. How many units would need to be sold each month to an after-tax target profit of $63,600? 5. Refer to the original data. Compute the company's margin of safety in both dollar and percentage terms. 6. What is the company's CM ratio? If monthly sales increase by $51,000 and there is no change in fixed expenses, by how much would you expect monthly net operating income to increase