Which unit rate corresponds to the proportional relationship shown in the graph with it's unit rate

Tom wants to order tickets online so that he and three of his friends can go to a water park the cost of the tickets is 16.00 per person there is also a 2.50 one-time service fee for ordering tickets online write an expression in term of n that represents the cost for n ordering tickets online

Icould really use some with this question.

Which two angles in the figure are adjacent angles?