Cab companies often charge a flat fee for picking someone up and then an additional fee per mile driven. The city of Charlotte, NC charges a $2.50 fee and and $2.50 per mile for each can ride.

In the context of this problem, the y-intercept represents the initial cost that a passenger incurs as soon as they step into the cab, before the cab travels any distance. This is the flat fee that the passenger has to pay regardless of the distance they intend to travel.

Given that the city of Charlotte, NC charges a $2.50 fee just for picking someone up, the y-intercept in this scenario would be $2.50. This means that the total cost starts at $2.50 when the distance traveled is zero miles. Hence, when you step into the cab, you immediately owe $2.50, even if you don't go anywhere.