rope is used up (4/5), and there is (5/6) m left, what is the original length of the rope in m?
一根绳子用去(4/5)，还剩(5/6)m，这根绳子原长多少m．
<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(5/6) / (1/5)</gadget>
<output>25/6 = around 4.166667</output>

<result>25/6 = around 4.166667</result>