A candle burns off its full length (2/5) for the first time, and burns the remaining (1/3) for the second time, leaving 12 cm. How long was the candle in cm?
一根蜡烛第一次燃去了全长的(2/5)，第二次又燃去了剩余的(1/3)，还剩12cm，这根蜡烛原来长多少cm？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">12 / (2/5)</gadget>
<output>30</output>

<result>30</result>