A and B are separated by a mountain. It takes 6.5 hours for someone to travel from A to B, and 7.5 hours to return from B to A. If he goes up the mountain at a speed of 3 km/h and down the mountain at a speed of 4 km/h, how many kilometers is the distance between A and B?
甲、乙两地相隔一座山岭，某人从甲地到乙地用6.5小时，从乙地回到甲地用7.5小时．他往返途中上山速度是3千米/时，下山速度是4千米/时，则甲、乙两地间的山岭路程有多少千米．
<gadget id="calculator">12 / 7</gadget>
<output>12/7 = around 1.714286</output>

<gadget id="calculator">14 * (12/7)</gadget>
<output>24</output>

<result>24</result>