Breakeven point using the contribution margin approach is calculated by: a. Adding fixed and variable costs and dividing by the sales price per unit. b. Subtracting variable costs from sales price and dividing that number by the selling price per unit. c. Subtracting variable costs from the selling price, adding fixed costs, and dividing by the number of units produced. d. Dividing total fixed costs by the difference between selling price and variable cost. I cannot choose between c and d. the text is very vague