An art professor wishes to take his class on a trip to the Art Institute of Chicago. The Art Institute has several different pricing options for groups:
$ 25 per person for group sizes up to 14 people (this is the standard individual rate);
$ 22 per person for group sizes from 15 to 25 people;
$ 18 per person for group sizes of 26 people or more.

For groups of at least 15 people, the group must also book their tickets ahead of time, and pay a flat reservation fee of $ 10. For groups of size 14 people or fewer, there is no reservation fee.

a) Fill in the missing values of the table showing the cost of admittance, for a group of people, for from 0 to 30, in increments of 5 people.


b) Write a piecewise function for .


c) How much will it cost to buy tickets for the professor plus 18 students?

d) If the professor's budget is $ 325, how many students can he take (that is, how many people in addition to himself)?