Mr. Louis received a prescription for 15 physiotherapy sessions.
The total cost to be expected for physiotherapy is 720 euros for the 15 sessions but the gentleman must pay for his sessions each week.
The physiotherapist, Mr. Ballestro, suggested that he do 3 sessions per week.
You now know the cost of a session since you have just calculated it (720€ divided by 15 or 48€).