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?
In the first fish tank, there are 7 goldfish + 8 beta fish = 
<gadget id="calculator">7+8</gadget>
<output>15</output>
15 fish.
The second fish tank therefore has 15 fish in the first tank * 2 = 
<gadget id="calculator">15*2</gadget>
<output>30</output>
30 fish.
So the third tank has 30 fish in the second fish tank / 3 = 
<gadget id="calculator">30/3</gadget>
<output>10</output>
10 fish.

<result>10</result>