I don't know what formulas to use. Please help!

Chapter 6: Applying Excel Data Unit sales Selling price per unit Variable expenses per unit Fixed expenses 20,000 units $60 per unit $45 per unit $240,000 Enter a formula into each of the cells marked with a ? below Review Problem: CVP Relationships Compute the CM ratio and variable expense ratio Selling price per unit Variable expenses per unit Contribution margin per unit ? per unit ? per unit ? per unit CM ratio Variable expense ratio ? ? Compute the break-even Break-even in unit sales Break-even in dollar sales ? units ? Compute the margin of safety Margin of safety in dollars Margin of safety percentage ? ? Compute the degree of operating leverage Sales Variable expenses Contribution margin Fixed expenses Net operating income ? ? ? ? ? Degree of operating leverage