Consider all 5 letter “words” made from the letters through (Recall, words are just strings of letters, not necessarily actual English words.)
- How many of these words are there total?
- How many of these words contain no repeated letters?
- How many of these words start with the sub-word “aha”?
- How many of these words either start with “aha” or end with “bah” or both?
- How many of the words containing no repeats also do not contain the sub-word “bad”?