For a rope, the full length (2/5) is 4m longer than the used one, and the remaining part is 2m longer than the used one. How many meters is the total length of this rope?
一条绳，用去全长的(2/5)多4m，剩下的部分比用去的多2m，这条绳全长多少米？
<gadget id="calculator">4 + 2 + 4</gadget>
<output>10</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5) - (2/5)</gadget>
<output>1/5 = around 0.2</output>

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

<result>50</result>