Wednesday, a local deli offered a lunch special consisting of a ham or roast beef sandwich with or without American cheese on toast, a roll, or a bagel. Thursday, the owner of the deli decided to offer customers the same options of meat and bread but let customers choose to have their sandwiches with or without either American or Swiss cheese. How many more one meat, one cheese, one bread sandwich combinations are offered Thursday than Wednesday?
1
6
12
18