The distance between port A and port B is 288 km. It takes 3.2 hours for a ship to travel along the current, and 4.8 hours to return against the current. Find the average speed of the ship to go back and forth.
甲、乙两港相距288km，一艘轮船顺水去时用了3.2小时，逆水返回时用了4.8小时，求这艘轮船往返的平均速度．
<gadget id="calculator">3.2 + 4.8</gadget>
<output>8</output>

<gadget id="calculator">2 / 8</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">288 * (1/4)</gadget>
<output>72</output>

<result>72</result>