If (2/3) of a 15-meter-long rope is used up, how many meters are left?
一根15米长的绳子，用了它的(2/3)，还剩下多少米．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">15 * (1/3)</gadget>
<output>5</output>

<result>5</result>