Answer:
Total cost = $24
Explanation:
In economics total cost is a combination of the amount actually paid for a product or activity and the forgone benefit of buying another product or doing another activity.
Opportunity cost is defined as the forgone alternative of doing a particular activity. For example of you can buy ice cream or a book, if you buy a book you forgot the pleasure you would have derived from taking the ice cream.
In this instance the actual cost of going to the movie is $9 while the foregone alternative is the $15 you would have earned as a coach.
Therefore
Total cost = 15 + 9 = $24
