A rope is used up (1/5) for the first time, and the remaining (1/5) is used up for the second time, with a difference of 2 meters between the two times. How long is the rope originally?
一根绳子第一次用去(1/5)，第二次又用去余下的(1/5)，两次相差2米．这根绳原来的长多少米．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(4/5) * (1/5)</gadget>
<output>4/25 = around 0.16</output>

<gadget id="calculator">(1/5) - (4/25)</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">2 / (1/25)</gadget>
<output>50</output>

<result>50</result>