After half of an iron wire is used up, the remaining half is used up. At this time, there are 9 meters left. How long is this iron wire?
一根铁丝用去一半后，再用去剩下的一半，这时剩下9米，原来这根铁丝多长？
<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 / (1/2) / (1/2)</gadget>
<output>36</output>

<result>36</result>