The table below shows the squares of different numbers:

number 2 -2 3 -3
(x)
square of the number 4 4 9 9
(y)

part a: does the table represent y as a function of x? justify your answer. (5 points)

part b: the total cost f(x), in dollars, for renting a rowboat for x hours is shown below:

f(x) = 20 + 3x

what is the value of f(150), and what does f(150) represent? (5 points)

The table in Part A represents y as a function of x. This means that the value of Y is dependent on the value of X. The table can be represented by an equation that describes the relation of X and Y:
or 
By substituting any value of X, you get a specific value of Y based from the given relationship, thus Y is a function of X. 

For Part B, the value of f(150) is $470 and it represents the total cost for borrowing a rowboat for 150 hours. By substituting the value of x = 150 into the function, you get the total cost: