Final answer:
The linear cost function for the parking garage is C(x) = 55x + 55(0.5), where x represents the number of hours used.
Step-by-step explanation:
The independent variable for this situation is the number of hours the parking garage is used, denoted by x. The dependent variable is the cost of using the parking garage, denoted by C(x).
A linear cost function for the situation is given by:
C(x) = 55x + 55(0.5)
The term 55x represents the cost for using the parking garage for x hours, and the term 55(0.5) represents the additional cost for every half-hour used.