If the red string is longer (1/4) than the green string, then how much shorter is the green string than the red string?
如果红绳比绿绳长(1/4)，那么绿绳比红绳短多少．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(1/4) / (5/4)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>