Find the total cost: $225 bill with a 35% markup

Which of the following statement about pascal's triangle are true?

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

Ihave trouble finding the nth term of a linear sequence