72

 https://www.google.com/search?q=72+ramayana

1. As per Padma Purana, duration of war between Lord Rama and Ravana lasted for 87 Days in which 15 Days there was no war. So, actual war fought for 72 Days.
2. Again in these 72 days the actual war between Lord Rama and Ravana lasted only for 7 days.

https://www.google.com/search?q=Padma+Purana