Edible! is a specialty popcorn store. It offers two varieties of popcorn: plain and flavored. The flavors range from Caramel Popcorn to Dark Chocolate Drizzled Popcorn to White Cheddar Popcorn. The plain popcorn sells for $4.15 per box and costs $0.70 per box to make. The flavored popcorn sells for $4.40 per box and costs $3.20 per box to make. Edible! has fixed costs per month of $3,977. Edible! sells 1 box of plain popcorn for every 4 boxes of flavored popcorn. How many boxes of plain popcorn and how many boxes of flavored popcorn must Edible! sell each month to break even? First identify the formula to compute the sales in units at various levels of operating income using the contribution margin approach. (Abbreviations used: Avg. = average, and CM = contribution margin.) Breakeven sales in units