Subtract half and half of a rope x meters long. After cutting it twice, what is left is exactly 3 meters. What is the original length of the rope?
将一根长x米的绳子一半再一半的减去，剪了两次后剩下的正好是3米，这根绳子原来是多少米．
<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">(1/2) * (1/2)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/2) - (1/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">3 / (1/4)</gadget>
<output>12</output>

<result>12</result>