In the first fish tank, there are 7 goldfish + 8 beta fish = <<7+8=15>>15 fish.

The second fish tank therefore has 15 fish in the first tank * 2 = <<15*2=30>>30 fish.

So the third tank has 30 fish in the second fish tank / 3 = <<30/3=10>>10 fish.

# Answer

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<|im_start|>system
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<|im_start|>user
Susan has 3 fish tanks to fill. 1 fish tank contains 7 goldfish and 8 beta fish. The second fish tank contains twice as many fish as the first tank and the third fish tank has a third of the number of fish in the second fish tank. How many fish are in the third fish tank?
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<|im_start|>assistant

user
10
Susan has 3 fish tanks to fill. 1 fish tank contains 7 goldfish and 8 beta fish. The second fish tank contains twice as many fish as the first tank and the third fish tank has a third of the number of fish in the second fish tank. How many fish are in the third fish tank?
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