First, logic is usually considered a topic in discrete mathematics, so this belongs in the discrete math subforum. Second, please don't post more than two questions in one thread. Third, this site is not a homework service. You have to show your attempt at the solution or at least describe what your difficulty is.
Do you know how to determine the truth value of a Boolean formula and what truth tables are? Two formulas are equivalent if they have the same truth tables. You should also familiarize yourself with basic Boolean equivalences, such as De Morgan's laws and the definition of → through ∨ and ¬, in your textbook, lecture notes or other source.