A car drives from place A to place B. When he goes there, he arrives at place B at 40 kilometers per hour, and when he returns, he returns at 60 kilometers per hour. What is the average speed of this car?
一辆车从甲地开往乙地，他去的时候是以每小时40千米到达乙地，回来时是以每小时60千米返回，这辆车的平均速度是多少？
<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">1 / 60</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/40) + (1/60)</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">2 / (1/24)</gadget>
<output>48</output>

<gadget id="calculator">1 * 48</gadget>
<output>48</output>

<result>48</result>