The distance between A and B is 378 kilometers. A car travels from A to B. It takes 4.3 hours to go there and 4.7 hours to return. Find the average round-trip speed.
甲乙两地相距378千米，一辆汽车从甲地开往乙地，去时用了4.3时，返回时用了4.7时，求往返的平均速度．
<gadget id="calculator">4.3 + 4.7</gadget>
<output>9</output>

<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">378 * (2/9)</gadget>
<output>84</output>

<result>84</result>