We will have the following
*First: We write the expressions that can be identified from the text:

&

Here "c" represents the cost of each course and "f" represents the service fee.
*Now, we subtract the second expression from the first, to determine the cost of each course, that is:
3270 = 5c + f
-2640 = -4c - f
----------------------
630 = c
So, we can see that the cost of each course is $630.
*Now, we replace the cost of each course into one of the initial equations to determine the value of "f":

So, the cost of the service fee is $120.
*We will have that the basic structure of the expression is:

So, the domain goes from all values that make the expression positive [ from x =1 to infinity].
And the range goes is defined from the least to the greatest, that is [x = 750 to infinity]. (This is when the number of courses equals 1, so the cost of the semester would be at minimum $750.