Alright, lets gets started.
Jullianne's start-up costs for the building, advertising, and supplies total $52,000.
she spends $680 on operating costs on daily basis.
Means Suppose the days d, the operating cost will be=
This cost will be added in her start up cost.
The earning for d days will be =
So, part A :
Now suppose after d days, she will start making profit means, after d days, her cost will be equal to her earning.
So, part B:
Subtracting 680 d from both sides
Dividing 280 in both sides
Means after 19 days, she will start making profit. : Answer
Hope it will help :)