The distance between A and B is 240 km. A car loaded with goods travels 40 km per hour from A to B, and 60 km per hour when returning empty. Find the average round trip speed of this car?
甲、乙两地相距240km，一辆汽车装载货物从甲地到乙地每小时行40km，空车返回时每小时行60km．求这辆汽车往返的平均速度？
<gadget id="calculator">240 / 40</gadget>
<output>6</output>

<gadget id="calculator">240 / 60</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">240 * (1/5)</gadget>
<output>48</output>

<result>48</result>