If a car travels from point A to point B at a speed of 60 km/h and returns from point B to point A at a speed of 40 km/h, what is the average speed of the car in km/h? ．
一辆汽车以每小时60千米的速度从A地开往B地，他又以每小时40千米的速度从B地返回A地，那么这辆汽车行驶的平均速度是多少千米/时．
<gadget id="calculator">1 + 1</gadget>
<output>2</output>

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

<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

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

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

<result>48</result>