There are 25 men and 20 women who belong to a club. an executive panel consisting of a president, vice president, secretary, and treasurer is being chosen. a) in how many ways cold the executive panel be chosen with no restrictions? b) in how many ways could the executive panel be chosen if it must include at least one woman and one man? c) in how many ways could the executive panel be chosen if the president and the vice president must have different genders?