91Ó°ÊÓ

Describe the following sets using set-builder notation. (a) \(\\{5,7,9, \ldots, 77,79\\}\) (b) the rational numbers that are strictly between -1 and 1 (c) the even integers (d) \(\\{-18,-9,0,9,18,27, \ldots\\}\)

How many singleton (one-element) sets are there in \(\mathcal{P}(A)\) if \(|A|=n\) ?

A person has four coins in his pocket: a penny, a nickel, a dime, and a quarter. How many different sums of money can he take out if he removes 3 coins at a time?