Philadelphia is 7 hours behind Bucharest
Best overlap: 3:00 PM to 6:00 PM in Bucharest is 8:00 AM to 11:00 AM in Philadelphia.
3:00 PM to 6:00 PM in Bucharest is when Philadelphia is also working, at 8:00 AM to 11:00 AM their time. Philadelphia is 7 hours behind Bucharest. That leaves about 3 hours of common time — enough for a meeting or two, so use it deliberately.