Which of the following is an exampke of thinking at the margin ? Deciding whether the benefit of working two extra hours per day is worth the sacrifice of study time

the answer would be in this answer. someone already asked the question.  

an informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.

answer; adjusting and adapting to a culture other than one's own;