Help I don’t understand the concept

Shiny white dental insurance costs $258 per year. approximately one-third of insured people need a filling, which averages $110 each. 80% of insured people get a preventive check-up each year, and the average cost of this visit is $95. if you consider shiny white’s income and expenses, what is the expected value of each insured customer?

F(n + 1) = f(n) – 8. if f(1) = 100, what is f(6)?

What describes horizontal cross section of the right rectangle 6m 8m 5m