There are 3 trumpets/flute x 5 flutes = <<3*5=15>>15 trumpet players
There are 15 players - 8 players = <<15-8=7>>7 trombone players
There are 7 players + 11 players = <<7+11=18>>18 drummers.
There are 2 clarinets/flute x 5 flutes = 10 clarinet players
There are 7 players + 3 players = <<7+3=10>>10 French horn players
In total 5 players + 15 players + 7 players + 18 players + 10 players + 10 players = <<5+15+7+18+10+10=65>>65 seats needed.
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