rope is 20 cm long, folded in half and cut along the middle, how much longer is the longer section than the shorter section.
一根绳子20厘米长，对折后沿中间剪开，长的一段比短的一段长多少厘米．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">20 * (1/4)</gadget>
<output>5</output>

<result>5</result>