20% of a rope is used up, and exactly 10 meters are used up. How many meters is this rope?
一根绳用去20%，正好用去了10米，这根绳有多少米？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">10 / (1/5)</gadget>
<output>50</output>

<result>50</result>