The length of a rope is equal to its own length (1/5) plus 20 meters, which is how many meters is the length of the rope.
一根绳子的长度等于它本身长度的(1/5)加上20米，这跟绳子长多少米．
<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">20 / (4/5)</gadget>
<output>25</output>

<result>25</result>