Northem Cruiseline offers nightly dinner cruises off the coast of Nanaimo and Victoria. Dinner cruise tickets sell for $80 per passenger. Northern Cruiseline's variable cost of providing the dinner. is $40 per passenger, and the fixed cost of operating the vessels (depreciation, salaries, docking fees, and other expenses) is $200,000 per month. The company's relevant range extends to 20,000 monthly passengers. The break-even units are 5,000 tickets sold. If Northern Cruiseline sells 9,000 dinner cruises, compute the margin of safety a. in units (dinner cruise tickets) b. in sales dollars c. as a percentage of sales a. Begin by determining the formula, and then compute the margin of safety in units (dinner cruise tickets). (Round your answer to the nearest whole number.) Sale price per unit Variable cost Margin of safety in units