Thank you for the opportunity to help you with your question!
An example of a decision that i have made in life is one of attending all my lectures. There are marginal benefits which accrue to this decision. First is that I am able to grasp the taught concepts from the word go which makes it easier for me to revise, secondly, I have a goo relationship with my lecturer hence i can ask any question that i do not understand and lastly, I record good grades in my finals. However, there also are marginal costs. First is that I miss out in most of the campus events and secondly, I disconnect with my peers who i lie hanging out with.
Hope this did assist. Please let me know if you need any clarification. I'm always happy to answer your questions. I will be pleased if you make me your private tutor.