Derby Phones is considering the introduction of a new model of headphones with the following price and cost characteristics. Sales price Variable costs Pixed conta 340 per unit 105 per unit 587,500 per month Required: a. What number must Derby sell per month to break even? b. What number must Derby sell to make an operating profit of $258,500 for the month? a. Break-even sales in units b. Number of units to be sold