A journey is divided into three sections: uphill, flat road, and downhill. The ratio of each section is 1:2:3. The ratio of the time it takes for a person to walk each section of the distance is 4:5:6. It is known that his speed is 3 kilometers per hour when going uphill, and the total length of the journey is 60 kilometers. How many hours did it take this person to complete the journey?
一段路程分成上坡、平路、下坡三段，各段路程之比依次是1：2：3．某人走各段路程所用时间之比依次是4：5：6，已知他上坡时速度为每小时3千米，路程全长60千米．此人走完全程用了多少小时？
<gadget id="calculator">1 + 2 + 3</gadget>
<output>6</output>

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

<gadget id="calculator">4 + 5 + 6</gadget>
<output>15</output>

<gadget id="calculator">4 / 15</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">(1/6) / 3 / (4/15)</gadget>
<output>5/24 = around 0.208333</output>

<gadget id="calculator">60 * (5/24)</gadget>
<output>25/2 = around 12.5</output>

<result>25/2 = around 12.5</result>