Mrs.  Fredrickson has 80 chickens where 1/4 are roosters and the rest are hens. Only three-fourths of those hens lay eggs. How many chickens does Mr. Fredrickson have that do not lay eggs?
Mrs. Fredrickson has 80 x 1/4 = <<80*1/4=20>>20 roosters.
So he has 80 - 20 = <<80-20=60>>60 hens.
Only 60 x 3/4 = <<60*3/4=45>>45 of the hens lay eggs.
Thus, 60 - 45 = <<60-45=15>>15 hens do not lay eggs.
Therefore, Mr. Fredrickson has a total of 15 hens + 20 roosters = <<15+20=35>>35 chickens that do not lay eggs.
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