After using up (3/5) of a rope, there is still (4/5) meters left, what is the length of the rope in meters?
一根绳子用去(3/5)后，还剩(4/5)米，这根绳子长多少米．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(4/5) / (2/5)</gadget>
<output>2</output>

<result>2</result>