For this case we have:
- Operating costs = $ 680 per day
Part A:
Since d is the variable that represents the number of days, we can represent an inequality for the gains given by:

Part B:
We want to know the moment from which Julianne obtains earnings, for that we clear d of the previous inequality:


To start making a profit, Julianne must work more than 186 days.
Answer:
