There are two candles of different lengths and thicknesses. The thick one can be lit for 6 hours, and the thin one can be lit for 4 hours. After two hours of burning, the lengths of the two candles are equal. How many more hours are lit? The length of the thick one is Twice the length of the thinner one.
有两只长短粗细都不相同的蜡烛，粗的能点6小时，细的能点4小时，点了两个小时以后两只蜡烛的长度相等，再点多少小时，粗的一只的长度是细的一只的长度的两倍．
<gadget id="calculator">2 - 1</gadget>
<output>1</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2 * (1/4)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/2) - (1/6)</gadget>
<output>1/3 = around 0.333333</output>

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

<gadget id="calculator">3 - 2</gadget>
<output>1</output>

<result>1</result>