You go to the movieplex where movies ordinarily cost $10. you are intending to see a movie for which you have a $3 off coupon good for only that movie at that time. however, when you get there you see a friend who asks if you would rather see a new release. both movies start and end at the same time. if you decide to see the new release with your friend, what is your opportunity cost?

Well, you couldn't use the coupon because its only for that one specific movie you were gonna see and since its at the same time as the new release, you couldn't reuse the coupon. If you do go with your friend, Its $10 a person. If you're paying for both of you, it would be $20. If you are paying for yourself, its just $10. If your friend has a coupon like you had (but for the new release and same time) then it would be $17 total if you paid for both tickets. Hope this helps :)