(1/5) of an iron wire is used for the first time, (1/5) meter is used for the first time, and 1 meter is used for the second time. What is the length of the iron wire in meters?
一根铁丝第一次用去它的(1/5)，第一次用去了(1/5)米，两次共用去了1米，这跟铁丝的长度为多少米．
<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</output>

<result>4</result>