The distance between A and B is 300 kilometers. It takes 5 hours for a car to drive from A to B, and 3 hours to return from B to A. What is the average speed of this car in kilometers?
甲乙两地相距300千米，一辆汽车从甲地开往乙地用了5小时，又从乙地返回甲地用了3小时，这辆汽车往返的平均速度是多少千米．
<gadget id="calculator">300 * 2</gadget>
<output>600</output>

<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">600 / 8</gadget>
<output>75</output>

<result>75</result>