A group of twelve seniors, seven juniors, six sophomores, and five freshmen must select a committee of four. How many committees are possible if the committee must contain the following? (a) one person from each class (b) any mixture of the classes (c) exactly two seniors

One of the complementary angles is 4 degrees mor than the other. find the angles (recall that complementary angles are angles whose sum is 90 degrees.) which of the following can not be used to solve the problem if x represents one of the angles? a. 2x-4=90 b. 2x+4=90 c. x+4=90