8) Dilbert Wireless Cellular sells phones for $1000. The unit variable cost per phone is $450 plus a selling commission of 10%. Fixed manufacturing costs total $12,250 per month, while fixed selling and administrative costs total $25,500. Required: a. What is the contribution margin per phone? b. What is the breakeven point in phones? C. How many phones must be sold to earn pretax income of $75,500