If (2/5) of a rope is cut off, there is still 8 meters left. What is the original length of this rope?
一根绳子，截去它的(2/5)，还剩下8米，这根绳子原来长多少．
<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">8 / (3/5)</gadget>
<output>40/3 = around 13.333333</output>

<result>40/3 = around 13.333333</result>