A rope is 42 meters long, if (3/7) of it is used up, how many meters are left?
一根绳子长42米，用去它的(3/7)，还剩多少米？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (3/7)</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">42 * (4/7)</gadget>
<output>24</output>

<result>24</result>