A big fish has a head length of 3 decimeters and a body length equal to the length of the head plus the length of the tail. The length of the tail is equal to the length of the head plus half the length of the body. How long is this big fish in meters?
一条大鱼，头长3分米，身长等于头长加尾长，尾长等于头长加一半身长，这条大鱼全长多少米？
<gadget id="calculator">3 + 12 + 9</gadget>
<output>24</output>

<gadget id="calculator">24 / 10</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>