When the young pioneers go out to camp, they walk 5 kilometers per hour when they go, and 3 kilometers per hour when they come back. What is the average speed of their round trips?
少先队员外出野营，去时每小时走5千米，回来时每小时行3千米，他们往返的平均速度多少多少．
<gadget id="calculator">1 * 2</gadget>
<output>2</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

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

<gadget id="calculator">(1/3) + (1/5)</gadget>
<output>8/15 = around 0.533333</output>

<gadget id="calculator">2 / (8/15)</gadget>
<output>15/4 = around 3.75</output>

<result>15/4 = around 3.75</result>