A store offers a discount if a customer purchases shirts in bulk. The table shows the relationship between the cost (c) in dollars per shirt and the number (s) of shirts purchased. Image of a table showing the cost in dollars per shirt based on the number of shirts purchased. When 3 shirts are purchased, the cost is 9 dollars and 50 cents per shirt . . . when 6 shirts are purchased, the cost is 9 dollars per shirt . . . when 9 shirts are purchased, the cost is 8 dollars and 50 cents per shirt . . . and when 12 shirts are purchased, the cost is 8 dollars per shirt.