Olaf has an aquarium. He has fish in 3 different colors: orange, green, and blue. Blue fish make up half of all the fish in the aquarium. There are 15 fewer orange fish than blue fish. How many green fish are there when the total number of fish in the aquarium is 80?
If there are 80 fish in total, then there are 80 fish / 2 = <<80/2=40>>40 blue fish.
The orange fish count is 15 less than blue, so it's 40 fish - 15 fish = 25 fish.
Olaf has then 80 fish - 25 fish - 40 fish = <<80-25-40=15>>15 green fish.
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