This is good information, but the question part is missing. Put the question in the comments and I'll try my best to help!
Can you repost with the picture please
For a non-resident:

For a resident:

We want to know the number of days
such that the two costs are equal ie 
To do this set the two costs equal to each other:


And solve for d:




The costs will be equal when a resident and a non-resident each use the beach for 12 days.
Answer:
(1,- 1.5)
Step-by-step explanation:
Sana po makatulong yan po sagot
Hope it help