Write a Cost Function for the Problem

Multiple Choice

Write a cost function for the problem. Assume that the relationship is linear.
-A cable TV company charges $21 for the basic service plus $7 for each movie channel. Let C(x) be the total cost in dollars of subscribing to cable TV, using x movie channels.

A) C(x) = 7x + 21
B) C(x) = 21x + 7
C) C(x) = 21x - 7
D) C(x) = 7x - 21