After using up (2/5) of a rope, there is still 75 meters left. How long is this rope?
一根绳子用去它的(2/5)后，还剩75米，这根绳子有多长？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">75 / (3/5)</gadget>
<output>125</output>

<result>125</result>