Hi Marybel,
This question requires a fully detailed response with graphs, tables, etc.
The following should help you get started:
The specific information your instructor may be looking for for number 1 will depend on the work you did in the course prior to this problem. He or she may be looking for you to make a table with one columns for the amount up from, another for the weekly costs, another for the equation for the full weekly cost, and one for the total cost keeping in mind the 4 weeks for the vacation.
For number 2 you will likely need to graph the equations from number 1, and include the images in the document you will submit to the instructor
For number 3, the fourth column from number one should help you out.
You are welcome to book a session for help with rest of the problem and/or a further explanation.