Casey's Cases sells cell phone cases in a mall kiosk. Casey charges $30 per case. The variable cost for a case, including the case, the royalty paid to the mall, and so on is $26. The monthly fixed cost for Casey's Cases is $2, 480. a. How many cases must Casey sell every month to break even? b. Casey believes that he can sell 700 cases a month. What is the margin of safety in terms of the number of cases