The table shows the outputs y for different inputs x:

input
(x): 3 7 11 15
output
(y): 4 6 8 10

part a: does the data in this table represent a function? justify your answer. (3 points)
part b: compare the data in the table with the relation f(x) = 5x – 21. which relation has a greater value when x = 11? (2 points)
part c: using the relation in part b, what is the value of x if f(x) = 99? (5 points)