Final answer:
The correct equation in slope-intercept form is y = 2x + 5. It represents the cost as a function of hours parked, with a flat fee of $5 (y-intercept) and an additional hourly charge of $2 (slope).
Step-by-step explanation:
The equation for the line in slope-intercept form representing the cost (y) as a function of the number of hours parked (x) is y = 2x + 5. This equation comes from the structure of the cost given by the public parking garage, which includes a flat fee and a rate that changes based on the hours parked. The flat fee represents the y-intercept, which is the cost when no hours have been parked (x=0), and it's given as $5. The additional $2 per hour represents the slope of the line because it's the rate at which the total cost increases for each additional hour parked. Therefore, the slope is 2, and the y-intercept is 5.