Please help, I'm behind

Diane owes $387 to her brother. if she debits her bank account $161.25 a month to pay him back, how many months will it take her to pay off the debt?

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

The border line of the linear inequality 4x + 7y < 5 is dotted true or false?