Use the graph to write an explicit function to represent the data and determine how much money amy earned in week 5.
graph with x axis labeled number of weeks and ranges from zero to seven, y axis labeled money earned, in dollars, and ranges from zero to one hundred eighty with points at one comma five, two comma fifteen, three comma forty five and four comma one hundred thirty five
f(n) = 5(3)n + 1; f(5) = 3,645
f(n) = 5(3)n; f(5) = 1,215
f(n) = 5(3)n − 1; f(5) = 405
f(n) = (3)n − 1; f(5) = 81