From A to B are all mountain roads. Among them, the uphill distance is (2/3) of the downhill distance, and the speed of a car uphill is half of the speed downhill, and it takes 7 hours to travel from A to B. How many hours does it take for the car to travel from point B to point A?
从甲地到乙地全部是山路．其中上山路程是下山路程的(2/3)，一辆汽车上山速度是下山速度的一半，从甲地到乙地共得7小时．这辆汽车从乙地返回甲地要行多少小时．
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / (1/6)</gadget>
<output>6</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

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

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

<gadget id="calculator">6 + 2</gadget>
<output>8</output>

<result>8</result>