A physicist uses a Geiger-Müller tube and counter to determine the beta activity of a vintage radium-dial pocket watch. Over a period of 300 s300\text{ s}300 s, the counter records a total of 513051305130 counts.
In a separate measurement with the pocket watch removed from the room, the counter records a background count of 144144144 counts over a duration of 480 s480\text{ s}480 s.
Calculate the corrected count rate of the pocket watch, in counts per second.