It took a ship 6 hours to sail from port A to port B, traveling 26 kilometers per hour. It took 1 hour longer to return because of the headwind. What is the average round trip speed of this ship in kilometers?
一艘轮船从甲港驶往乙港用了6小时，每小时行26千米，返回时因为逆水比去时多用了1小时．求这艘轮船往返的平均速度是多少千米？
<gadget id="calculator">26 * 6 * 2</gadget>
<output>312</output>

<gadget id="calculator">6 + 1 + 6</gadget>
<output>13</output>

<gadget id="calculator">312 / 13</gadget>
<output>24</output>

<result>24</result>