Apackage of 4 mechanical pencils comes with 2 free erasers and if you get a total of 12 eraser how many packages of pencils did you buy

Quick! a survey of 57 customers was taken at a bookstore regarding the types of books purchased. the survey found that 33 customers purchased mysteries, 25 purchased science fiction, 18 purchased romance novels, 12 purchased mysteries and science fiction, 9 purchased mysteries and romance novels, 6 purchased science fiction and romance novels, and 2 purchased all three types of books. a) how many of the customers surveyed purchased only mysteries? b) how many purchased mysteries and science fiction, but not romance novels? c) how many purchased mysteries or science fiction? d) how many purchased mysteries or science fiction, but not romance novels? e) how many purchased exactly two types of books?

Ithink i know it but i want to be sure so can you me out ?

You went to a restaurant and spent $53.25 on the meal. there was a 6% sales tax. what was the amount of money, not including a tip, you spent at the restaurant?