Final answer:
The last day the PT can see the patient is Thursday.
Step-by-step explanation:
The last day the PT can see the patient is Thursday. Since the patient desires to schedule an additional appointment for the following week, and today's session is on a Friday, we can count 7 days from Friday to the next Friday. Continuing from there, we can count 7 days again to the next Thursday. Therefore, Thursday would be the last day the PT can see the patient.