(4 points) Suppose you are watching ten people leaving a bookstore. The clerk in the bookstore says that they sold a total of seven cookbooks and five C programming books to these ten customers. You are also told that one of the ten people didnt buy anything and no one person purchased multiple copies a single text, but some may have purchased one of each. You must show your work to receive full credit.

a) How many people purchased at least one book?

b) How many people purchased only the cookbook?

c) How many people purchased both a cookbook and a network programming book?

*** you must show your work!