In $2008$ subway started a $$5$ foot long campaign. Varible costs in $2008$ were approximately $30\%$ of sales and while fixed costs increased due to its $$5$ sub promotion, fixed cost did not increase by a significant amount. Volume of sales increased significantly which included the benefit of additional sales of other high profit items like soda and chips due to increased traffic. Discuss the relationship among cost, volume and profit of which subway took advantage along the way and how that relationship shifted the promotion along the scale of profitability during its $13$ year $$5$ foot long promotion