Riyadh is 6 hours ahead of Brasília
Best overlap: 8:00 AM to 12:00 PM in Brasília is 2:00 PM to 6:00 PM in Riyadh.
The hours that work for both Brasília and Riyadh are 8:00 AM to 12:00 PM (Brasília) and 2:00 PM to 6:00 PM (Riyadh). The shared window is roughly 4 hours; treat its midpoint as the default and you'll keep both teams happy.