Consider all 6 letter "words" made from the letters a through j. (In this context words are just strings of letters, not necessarily actual English words.)
Part a
How many of these words are there total?
Part b
How many of these words contain no repeated letters?
Part c
How many of these words start with the sub-word "kid"?
Part d
How many of these words either start with "aha" or end with "bah" or both?
Part e
How many of the words containing no repeats also do not contain the sub-word "hid"?