wire is 100 meters long, and 40 meters are used up, how much of the wire is used up
一根铁丝长100米，用去40米，用去这根铁丝的多少
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>