Mrs. Amaro has 80 x 3/4 = <<80*3/4=60>>60 red roses.
So, 80 - 60 = <<80-60=20>>20 roses are not red.
Then, 20 x 1/4 = 5 of those 20 non-red roses are yellow.
Hence, 20 - 5 = <<20-5=15>>15 roses are white.
Therefore, 60 + 15 = <<60+15=75>>75 roses are either red or white.
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