Jen attends a violin concert this Friday night. The ticket for the concert is $15.She is also considering other alternative uses of his time including the following three possibilities: I) working at a caf and earning $20, II) baby-sitting a child and earning $40, III) writing a term paper, which she values at $30. If she had not attended the concert, she can do either I), II), or III). What is the accounting cost of attending the violin concert this Friday night? What is the economic cost of attending the violin concert this Friday night?