A big shark has a head length of 3 meters 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 half of the sum of the length of the head plus the length of the body.
一条大鲨鱼，头长3米，身长等于头长加尾长，尾长等于头长加身长和的一半，这条大鲨鱼全长多少米？
<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(3/2) + 3</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(9/2) / (1/2)</gadget>
<output>9</output>

<gadget id="calculator">2 * 9</gadget>
<output>18</output>

<result>18</result>