The distance between A and B is 60 kilometers. It takes 4 hours for the ship to travel from A to B, and 6 hours to return from B to A. What is the average speed of the round trip of the ship?
甲、乙两个码头之间相距60千米，轮船从甲地到乙地用了4小时，由乙地返回甲地用了6小时．求轮船往返一次的平均速度是多少？
<gadget id="calculator">6 + 4</gadget>
<output>10</output>

<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">60 * (1/5)</gadget>
<output>12</output>

<result>12</result>