# discrete math

posted by
**carlton** on
.

How many strings of five uppercase English letters are there

(a) that start or end with the letters BO (in the order), if letters can be repeated? (inclusive or)

(b) that start with an X, if letters can be repeated?

(c) that start with the letters BO (in that order), if letters can be repeated?

(d) if letters can be repeated?