There are two candles of different thickness but the same length, and they are lit at the same time. After 1 hour, the thin candle is shortened by 15 cm, while the thick candle is only shortened by 3 cm. At this time, the length of the thick candle is exactly three times that of the thin candle. Question: How long will the thick candle last?
有两根粗细不同但长度相同的蜡烛，把它们同时点燃，1小时后细蜡烛缩短了15厘米，而粗蜡烛只缩短了3厘米，此时粗蜡烛长度正好是细蜡烛的3倍．请问：粗蜡烛还能烧多久？
<gadget id="calculator">15 - 3</gadget>
<output>12</output>

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

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

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

<gadget id="calculator">6 * 1</gadget>
<output>6</output>

<result>6</result>