If Adelaide bought 30 ducks, Ephraim bought 30 ducks / 2 = <<30/2=15>>15 ducks.
Since Ephraim bought 45 fewer ducks than Kolton, Kolton bought 45 ducks + 15 ducks = <<45+15=60>>60 ducks
The total number of ducks the three bought is 60 ducks + 15 ducks + 30 ducks = <<60+15+30=105>>105 ducks
The average number of ducks each bought is 105 ducks / 3 people = <<105/3=35>>35 ducks/person
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