As discussed in the lecture notes, stacks are a very commonly used abstract data type. applications of stacks include implementation of reverse polish notation expression evaluation and undo buffers. stacks can also be used to check whether an expression has balanced parentheses, braces, and brackets (,{,[ or not. for example, expressions with balanced parentheses are "(x + y)", "{x + (y + z)}"

Arecipients list has been loaded into a document. which commands should be clicked in order to filter the list so that letters will not be printed for recipients who live in a certain state? mailings tab, start mail merge, select recipients, type new list, then insert only contacts from the desired states mailings tab, rules, select recipients, use existing list, then choose a recipients list that includes only contacts in certain states mailings tab, select recipients, use existing list, rules, fill in, then type in certain states mailings tab, rules, skip record select “state” under field name, then type in the state name under “equal to”