Quadratic Vertex Word Problems

Kelly has a bike rental business in the small town she currently lives. She currently rents out her bikes at $10$ dollars per bike per hour. In high season, she averages $45$ hours of rentals a day.

She notices that for every dollar increased, she loses about $3$ hours of rentals a day.

Kelly hopes to maximize income in high season. Let be $y$ the total income and let $x$ be the number of times Kelly increases rental price by a dollar.