Help mee please I would really appreciate

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

Solve the equation x/4 - 5= -8 -27 -12 -7 12

Use sigma notation to represent the following series for 9 terms.