12. Suppose A, B, and C represent three bus routes through the suburb of a city. Let A, B, and C' also be sets whose elements are the bus stops for the corresponding bus route. Suppose A has 25 stops, B has 30 stops, and C has 40 stops. Suppose further that A and B share (have in common) 6 stops, A and C share 5 stops, and B and C share 4 stops. Lastly, suppose that A, B, and C share 2 stops. Answer each of the following questions (a) How many distinct stops are on the three bus routes? b) How many stops of A are not stops for both B and for C