A bicycle travels from A to B at a speed of 20 kilometers per hour, and immediately returns to A at a speed of 30 kilometers per hour. If the distance between the two places is 120 kilometers, what is the average speed of the bicycle in kilometers?
自行车以每小时20千米的速度从甲地到乙地，到达后立即以每小时30千米的速度返回甲地．如两地相距120千米，该自行车的平均速度是多少千米．
<gadget id="calculator">120 / 20</gadget>
<output>6</output>

<gadget id="calculator">120 / 30</gadget>
<output>4</output>

<gadget id="calculator">6 + 4</gadget>
<output>10</output>

<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">120 * (1/5)</gadget>
<output>24</output>

<result>24</result>