Mr. Hartzel had 12 books in his home library. He bought 9 new books at the bookstore, then he sold 6 books. How many books does Mr. Hartzel have now?

What is the result of converting 60 ounces to pounds remember there are 16 ounces in a pound

In a two-digit number the units' digit is 7 more than the tens' digit. the number with digits reversed is three times as large as the sum of the original number and the two digits. find the number.

According to a study conducted in 2015, 18% of shoppers said that they prefer to buy generic instead of name-brand products. suppose that in a recent sample of 1500 shoppers, 315 stated that they prefer to buy generic instead of name-brand products. at a 5% significance level, can you conclude that the proportion of all shoppers who currently prefer to buy generic instead of name-brand products is higher than .18? use both the p-value and the critical-value approaches.