The table below shows the cube roots of different numbers
Number(x) 8 27 64 125
Cube root(y) 2 3 4 5

Part A: Does the table represent y as a function of x? Justify your answer.
Part B: The total cost f(x), in dollars, for renting a bike for x hours is shown below:

f(x) = 10 + 20x

What is the value of f(100), and what does f(100) represent?