The Petersonian alphabet consists of the 5 letters: O, R, Z, S, T. Any sequence of 1-7 letters is a valid word in this language (including words with repeated letters). How many different words does the Petersonian language contain?
When trying to find combinations, we multiply the numbers of things we can add to it. There are 6 different types of bread, 4 different types of meat, and 7 different types of condiments plus the no condiment. Since for the meat and condiment, there's another possible outcome than having just 1 type of meat and no condiment, we multiply by two twice.
This means we have 6*4*2*7*2=672 different sandwiches.