MT&A uses the function, f(x) = 475 - 15x, to depreciate smart phones, where f represents the value of a smart phone and x represents the number of months since its purchase. Part A: Find f-1, and explain what it represents in this situation. Part B: When will the depreciated value of a smart phone be less than $100? Part C: What does x represent in f-1(x) = 30? What is the value of x