After a rope is cut off (2/5). There are 15 meters left, how many meters is the length of this rope?
一根绳子剪去(2/5)后．还剩15米，这根绳子原来长多少米．
<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">15 / (3/5)</gadget>
<output>25</output>

<result>25</result>