In the following scenario, what is the opportunity cost of taking the trip?
You can either A. spend time working and making x amount of $.
Or B. you can take a trip that will cost you X amount of $.
What is the opportunity cost of the trip?
If you are going to determine the opportunity cost for the trip, you have to include two things. First, you have to include the actual cost of making the trip. Then, you have to factor in what you would have made if you had gone to work instead of taking the trip (assuming that you are not on paid vacation while you are on the trip). This is because opportunity cost (in this case) is what you are giving up to go on the trip. You are giving up both the cost of the trip and the money that you would have made working.
To be technical, the opportunity cost is not the money. It is what you would have done with the money. So your opportunity cost is whatever you would have done with the sum of the cost of the trip plus the money you would have made working.
The opportunity cost of taking the trip is spending time working and making x amount of $.