The distance between A and B is 120 kilometers. A car travels from A to B at 40 kilometers per hour and returns at 60 kilometers per hour. What is the average speed of this car going back and forth between the two places in kilometers per hour?
甲乙两地相距120千米，一辆汽车从甲地开往乙地，每小时行40千米，返回时每小行60千米，这辆汽车往返两地的平均速度是每小时多少千米
<gadget id="calculator">120 * 2</gadget>
<output>240</output>

<gadget id="calculator">120 / 40</gadget>
<output>3</output>

<gadget id="calculator">120 / 60</gadget>
<output>2</output>

<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">240 / 5</gadget>
<output>48</output>

<result>48</result>