First find the total number of pieces of mail the post office receives per day: 60 letters + 20 packages = <<60+20=80>>80 pieces of mail
Then multiply the daily amount of mail by the number of days per month: 80 pieces/day * 30 days/month = <<80*30=2400>>2400 pieces/month
Then multiply that number by 6 to find the total number of pieces of mail handled: 2400 pieces/month * 6 months = <<2400*6=14400>>14400 pieces
#### 14400