The answer that I got is 3/7, because the deli uses one type of bread, one type of cheese, and one type of meat. When you count the total types of sandwich foods, it adds to a total of 7 but since they only use 3 of the 7 altogether the probability in a fraction would be 3/7. And because you can't simplify 3/7, your answer is just 3/7.
Hope this helps!! Tell me if it did or didn't, and if you need anymore help on anything, i'll be happy to help as much as I can!! :-)