Answer:
Take the trip because the cost of the trip is less than her benefit.
Explanation:
Susan should absolutely take the trip because the cost of it is far less than her benefit.
Not only is it because of her personal assessment of the benefit of the trip: she claims that the trip will give her twice the benefit than the total cost of $5,000, but also because the opportunity cost of $4,000 (what she would earn if she continued to work) is not very high.