Part A : Yes, it represents y as a function of x. There are not 2 different y values for the same x value. f ( x ) = ∛ x ( or : y = ∛x ) Part B : f ( x ) = 10 + 20 x f ( 100 ) = 10 + 20 · 100 = 10 + 2,000 = 2,010 f ( 100 ) represents the total cost for renting a bike for 100 hours.